A, B and D are already rational numbers, 0.4 itself is a rational number, two rational numbers make a product of rational number.
So A, B, D are the correct choices.
Are you sure it asks for rational numbers, not irrational number?
By the recursive definition,




Step-by-step explanation:
5:3=35
5=35×3
5=105
5÷105=0.05

Both the numerator and denominator are continuous at

, which means the quotient rule for limits applies:

Perhaps you meant to write that

instead? In that case, you would have