What is a conditional statement in programming?

A conditional statement in programming is a construct that allows a program to execute certain blocks of code depending on whether a specified condition evaluates to true or false. This is fundamental in controlling the flow of a program, enabling it to make decisions based on dynamic inputs or conditions.

For instance, an "if" statement is a common type of conditional that evaluates a condition, and if that condition is true, the code within that block runs. If the condition is false, the code does not execute, which can lead to alternative actions being taken if there's an "else" clause.

The other options highlight concepts related to programming but do not accurately define a conditional statement. A variable holding true or false values refers to boolean variables, which are used within conditional statements but are not themselves conditional statements. A function that always returns true does not involve any condition and lacks the decision-making aspect pivotal to conditional statements. Similarly, a loop that iterates under specific conditions pertains to repetition of code rather than conditionally executing code, distinguishing it from the nature of conditional statements.