Can someone me i am stuck on my homework.

1. which polynomial represents a sum of cubes?
a.) x^3-64
b.) 8x^3+125
c.) 16x^3 + 1
d.) 27x^3+4

2. which of the following polynomials represents a difference of squares?
a.) 9x^2-49
b.) 16x^2+81
c.) 25x^2+100
d.)6x^2-121