Final answer:
Both a and b must either be rational or irrational to satisfy the equation 4ab = 4 being irrational; however, the statement does not provide enough data to ascertain which is the case.
Step-by-step explanation:
The statement 4ab = 4 is irrational suggests that the product of a and b when multiplied by 4 is an irrational number. If we divide both sides of the equation by 4, we get ab = 1. For this equation to hold, if one of the numbers, say a, is rational (meaning it can be expressed as the ratio of two integers), then b must also be rational because the ratio of two rationals is always rational. On the other hand, if a is irrational, then b must be irrational as well to maintain the product as an irrational number. Therefore, the conclusion is that either both a and b are rational or both a and b are irrational. Hence, the correct option is either both are rational or both are irrational, but the statement does not have enough information to determine which is the actual case.