Which of the following is not true about Global Variables:

Answer: The statement "A function that uses global variables does not suffer from reusability." is not true — functions that use global variables do suffer from reduced reusability.

Why this is false:

• Hidden dependencies: the function relies on external state not visible in its signature, which hinders reuse in other contexts.

• Side effects: global variables can be modified by different parts of the program, making behavior unpredictable and hard to isolate.

• Testing and maintenance: functions depending on globals are harder to unit-test and to reason about, reducing maintainability and reusability.

• Concurrency and namespace issues: globals can cause race conditions in concurrent code and naming collisions in large codebases.

Why the other statements are true:

• The values of global variables accessed by a called function may be changed inadvertently by that function, producing unexpected side effects.

• Functions are intended to be independent modules; using globals creates implicit coupling and removes that independence.

• When functions rely on global variables, it is not immediately apparent which values are being used, hiding dependencies from readers.

Recommendation: prefer passing required data explicitly via parameters, keep functions pure when possible, and minimize use of mutable global state to improve reusability, testability, and maintainability.