:D funny one...
I'm sorry.... Maybe I did not explain it clearly enough... Use the spoiler function at the end of the post.
Anyhow, a^2 + a = 6 is a second degree equation:
a^2 + a - 6 = 0, with -3 and 2 as solutions.
With that in mind, we can check all equations and quickly see if -3 or 2 is among them:
A has solutions 2 and -2 - out
B has solutions 3 and -3 - out
C has solution 2 - out
D has solutions 2 and 3 - out
E has solutions 3 and -2 - correct.

Here is how you should do it with the spoiler (only that I'm not un-ticking that "Disable.... "): [spoiler]E[/spoiler]. Press once before the text you want to hide and again at the end of the text.

DanaJ wrote: funny one...
I'm sorry.... Maybe I did not explain it clearly enough... Use the spoiler function at the end of the post.
Anyhow, a^2 + a = 6 is a second degree equation:
a^2 + a - 6 = 0, with -3 and 2 as solutions.
With that in mind, we can check all equations and quickly see if -3 or 2 is among them:
A has solutions 2 and -2 - out
B has solutions 3 and -3 - out
C has solution 2 - out
D has solutions 2 and 3 - out
E has solutions 3 and -2 - correct.

Here is how you should do it with the spoiler (only that I'm not un-ticking that "Disable.... "): E. Press once before the text you want to hide and again at the end of the text.

Who knows who really is kidding, you are laughing, I am

Answer is E