What do decrement operators do in programming?

Decrement operators are specifically designed to reduce the value of a variable by one. In Java, the decrement operator is represented by the symbol "--." When applied to a variable, it effectively reduces that variable's value by one, thus performing a subtraction operation.

For example, if a variable x initially has a value of 5 and you apply the decrement operator (i.e., x-- or --x), the new value of x will be 4. This helps in scenarios like loops or counters where you need to decrease a value iteratively.

The other options do not accurately reflect the function of decrement operators. Multiplying a variable by one does not change its value, adding one to a variable is the function of the increment operator, and stating that both adding and subtracting occur does not hold since decrement specifically denotes only subtraction. Thus, the correct understanding of decrement operators is that they solely subtract one from a variable.