True or False: A function can be used within an expression, whereas a subroutine (void method) cannot be used as an expression operand.

Introduction / Context:
This focuses on expression usage in C#: values versus statements. A function that returns a value can appear in expressions; a void method cannot, because it yields no value.

Given Data / Assumptions:

• Function: non-void return type, produces a value.
• Subroutine: void return type, produces no value.

Concept / Approach:
Expressions require operands that evaluate to values. Using a void-returning method where a value is expected causes a compile-time error. Void methods are invoked as standalone statements.

Step-by-Step Solution:

Verification / Alternative check:
Try compiling code that assigns the result of a void method; the compiler rejects it.

Why Other Options Are Wrong:

• False: Would imply void methods can yield values for expressions, which is incorrect.

Common Pitfalls:
Assuming any method call can be nested in expressions regardless of return type.

Final Answer:
True