To solve this, we need to find out which pair consists of a number and its square. This means that the second number in the pair will be the result of the first number multiplied by itself. We're going to check each pair one by one.
A. First, let's look at the pair (2, 4). If we calculate the square of 2, which is 2 * 2 = 4, we observe that indeed it matches with the second number of the pair.
After checking the first pair, we have found that (2, 4) meets the condition, with 2 being a whole number and 4 being the square of 2. So, the true answer is (a). After finding the correct answer, we don't need to check the rest of the pairs.