Which of the following relations is a function

It is b. 1,2 . 3,2 .  1,4

If you would like to simplify 2a^2b^3 * (4a^2 + 3ab^2 - ab), you can do this using the following steps:

2a^2b^3 * (4a^2 + 3ab^2 - ab) = 2a^2b^3 * 4a^2 + 2a^2b^3 * 3ab^2 - 2a^2b^3 * ab = 8a^4b^3 + 6a^3b^5 - 2a^3b^4

The correct result would be d. 8a^4b^3 + 6a^3b^5 - 2a^3b^4.