Distributive property of

14+28

You take out the GCF. The GCF here is 14. Since 14 can go both into 14 and 28 and is the largest number than can do so. 7 isn't because 14 is larger. So take the GCF out and you have this:

14(1+2)

Parenthesis indicate multiplication just in case you didn't know. That's your final answer since there is not GCF of 1 and 2

The correct answer is: b