Answer: A) 4^9
The rule you use is
a^b * a^c = a^(b+c)
The base stays the same at 'a' the whole time. We add the exponents. If the bases were different on the left hand side, then we cannot use this rule.
In this case, a = 4, b = 6, c = 3.
4^6 * 4^3 = 4^(6+3) = 4^9
