The answer you selected in that photo given, is correct. I can tell just by using common sense and by judging the other options second option (B) is looking the most clearest one to me.
Two planes intersect at a line. Not a point.
Group like terms , factor out common variable.
(xz+x) + (yz+y)
x(z+1) + y(z+1)
factor out (z+1)
= (z+1)(x+y)
= solution C.
Answer: 
Step-by-step explanation:
1. By definition, the associative property of addition is:

This property says that you can group the numbers in different ways and you will obtain the same result.
2. Therefore, if you have the following expression:

You apply the Asociative property of addition by regrouping the numbers as following:

3. Then, you can conclude that the correct option is B.
So, put your "x's" together first and then your intercepts. That should answer your question :)