In C input/output programming, which standard library function is most appropriate for reading a multi-word string that includes spaces from standard input?

Introduction / Context:Reading text that contains spaces (for example, full names or sentences) requires care in C. Basic token-oriented input like scanf with the %s specifier stops at whitespace, which truncates multi-word input. Older C textbooks often used gets to read an entire line including spaces. Although gets is now removed from the C standard due to safety issues, understanding why it was historically chosen explains the intended behavior of multi-word input questions and highlights safer modern alternatives.

Given Data / Assumptions:

• The task is to read a string that can include spaces (multi-word).
• We are comparing classic C standard I/O functions.
• We focus on functional suitability for capturing spaces, not security best practices.

Concept / Approach:

• scanf with %s reads until the first whitespace, so it fails for multi-word input.
• gets historically read an entire line up to the newline, thus capturing spaces.
• printf and puts are output functions and cannot read input at all.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• printf(): Output only; cannot read.
• scanf(): With %s, it stops at whitespace; does not capture multi-word strings without complex formats.
• puts(): Output only; prints a string with a newline.

Common Pitfalls:

• Using gets in real code is unsafe because it cannot prevent buffer overflows. Prefer fgets(buffer, size, stdin) in modern C.
• Assuming scanf("%[^]") is trivial; while it can read lines, it requires careful width limits to avoid overflow.

Final Answer: