WGU D278 (OA) – File Handling, Exceptions, and Object-Oriented Programming Full Objective Assessment (2025 Edition) | Comprehensive Real Question Final Exam | Python Scripting & Programming Foundations | Verified Answers with Detailed Rationales

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WGU D278 OA – File Handling, Exceptions,
and Object-Oriented Programming | Full
Objective Assessment (2025 Edition)
Comprehensive Real Question Final Exam | Python Scripting & Programming
Foundations | Verified Answers with Detailed Rationales


Overview:

This WGU D278 Scripting and Programming Foundations – File Handling & OOP Master
Exam (2025) is a complete actual -question objective assessment designed to mirror the real
WGU D278 OA.
It provides full coverage of:

 Python File Input/Output (I/O) – Reading, writing, appending, and managing text and
binary files
 Exception Handling & Error Recovery – Using try, except, else, and finally
correctly
 Context Managers and Resource Management – Safe file closing and automation with
with statements
 Object-Oriented Programming (OOP) – Classes, inheritance, polymorphism,
encapsulation, and class methods
 Data Serialization – Working with CSV and JSON files
 Applied Code Scenarios – Debugging and interpreting file-based logic questions

Each question includes bolded correct answers and detailed rationales, making it ideal for
both exam preparation and hands-on Python mastery.




1. Which mode opens a file for writing, erasing its contents if it already exists?

A) 'r'
B) 'w'

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C) 'a'
D) 'r+'

Rationale 'w' mode overwrites the existing file or creates a new one.



2. What will happen if you try to open a non-existent file using
open('missing.txt', 'r')?

A) It creates a new file.
B) It prints “File not found.”
C) It raises a FileNotFoundError.
D) It returns an empty string.

Rationale Reading a non-existent file triggers FileNotFoundError.



3. What does the 'a' mode do in open()?

A) Opens file for reading.
B) Opens file for appending data at the end.
C) Opens file for writing from start.
D) Opens file in binary mode.

Rationale 'a' mode appends new content without overwriting.



4. What is the correct way to close an opened file in Python?

A) file.stop()
B) close(file)
C) file.close()
D) end(file)

Rationale The .close() method closes the file stream.

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5. What is printed by this code?

with open("demo.txt", "w") as f:
f.write("Data")
print(f.closed)

A) False
B) True
C) Data
D) Error

Rationale Using a with statement auto-closes the file after the block.



6. What method reads the entire contents of a text file as a string?

A) file.readline()
B) file.read()
C) file.readlines()
D) file.input()

Rationale read() reads the full file content into one string.



7. What will this code print if data.txt contains:

Hello
World
f = open("data.txt")
print(f.readline())

A) HelloWorld
B) Hello
C) World
D) ['Hello', 'World']

Rationale .readline() reads only the first line of the file.

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8. Which method returns a list of all lines in a file?

A) read()
B) readlines()
C) readline()
D) lines()

Rationale readlines() loads each line as an element of a list.



9. What does 'b' indicate in a file mode string like 'rb'?

A) Backup
B) Binary mode
C) Both read and write
D) Background

Rationale 'b' means the file is opened in binary mode.



10. Which statement correctly writes multiple lines to a file?

lines = ["A\n", "B\n", "C\n"]

A) file.write(lines)
B) file.add(lines)
C) file.writelines(lines)
D) file.append(lines)

Rationale .writelines() writes a list of strings to a file.



11. What does the following code do?

f = open("notes.txt", "r+")