4^(6)x4^(3)

a ) 4^9
b ) 4^18
c ) 12^9
d ) 64^9

To find the product of these two exponents, you would add the exponents together.

Therefore, 4^(6) x 4^(3) = 4^(6+3) = 4^9.

So the correct answer is option a) 4^9.