If you mean (h^(7/3))(h^(14/3)), this is h^(7/3+14/3)=h^(21/3)=h⁷. None of the given answers.
If you mean ((h⁷)/3)((h¹⁴)/3), this is (h²¹)/9, none of the given answers.
If you mean ((h⁷)³)(h¹⁴/3), this is h²¹(h¹⁴/3)=h³⁵/3, answer A.
So what did you mean?