Which expression is a difference of cubes? 9w^33-y^12 18p^15-q^21 36a^22-b^16 64c^15 - a^26

For binomial to be a difference of cubes, both terms must be perfect cubes:

For

9w^33-y^12

The first term is not a perfect cube because of 9

For

8p^15-q^21

Both terms are perfect cube

For

36a^22-b^16

The first term is not a perfect cube because of 36

For

64c^15 - a^26

The second term is not a perfect cube because of the exponent of a which is 26