Answer:
Sadly, you are wrong. The right answer is the 3rd one.
Explanation:
Basically, a constant term basically means a term that contains only a number, and all the other ones have a variable other than 8, which means it has to be 8. Second, the exponent of the 3rd term, which is 3y, is 1 since the exponent is what you would call the small number at the top right of a number (I guess?). Basically, if there is no exponent, the exponent is 1.