Step 1: Understanding the Concept:
A case-sensitive programming language distinguishes between uppercase and lowercase letters in identifiers, keywords, and variable names.
Step 2: Detailed Explanation:
Let us review the properties of the listed programming languages:
- FORTRAN: Case-insensitive; variables like SUM and sum are treated as identical.
- BASIC: Case-insensitive; variables and keywords can be written in any letter case.
- C: Case-sensitive; the compiler distinguishes count, Count, and COUNT as three distinct identifiers.
Thus, C is a case-sensitive programming language.
Step 3: Final Answer
The correct option is (C).