The instructions in a . . . . . . . . loop are always processed at least once, whereas the instructions in a . . . . . . . . loop might not be processed at all.

The correct answer is: B. Pretest, posttest

A pretest loop is a type of loop that checks the condition before the loop body is executed. If the condition is true, the loop body is executed. If the condition is false, the loop terminates.

A posttest loop is a type of loop that checks the condition after the loop body is executed. If the condition is true, the loop body is executed again. If the condition is false, the loop terminates.

In a pretest loop, the instructions in the loop body are always processed at least once, because the condition is checked before the loop body is executed. In a posttest loop, the instructions in the loop body might not be processed at all, because the condition is checked after the loop body is executed.

For example, the following code shows a pretest loop:

int i = 0;
while (i < 10) {
System.out.println(i);
i++;
}

In this code, the loop body (the statement System.out.println(i)) is always executed at least once, because the condition i < 10 is checked before the loop body is executed. The loop will continue to execute as long as the condition is true. When the condition becomes false (when i is equal to 10), the loop will terminate.

The following code shows a posttest loop:

int i = 0;
do {
System.out.println(i);
i++;
} while (i < 10);

In this code, the loop body (the statement System.out.println(i)) might not be executed at all, because the condition i < 10 is checked after the loop body is executed. The loop will execute the loop body at least once, but it might continue to execute the loop body even after the condition becomes false. The loop will only terminate when the condition becomes false and the loop body does not change the value of i.