[tex] \frac{2^5}{8}=2^2 [/tex]. If we change the 8 into a base of 2 raised to the 3rd power we can use the Quotient rule for exponents. Rewriting we have [tex] \frac{2^5}{2^3} [/tex]. The rule is that if the bases are the same (which they are) we can subtract the exponents, lower from upper. [tex] 2^{5-3}=2^2 [/tex]. So the reason we will choose is the third one: By simplifying 8 to [tex] 2^3 [/tex] to make both powers base 2, and subtracting the exponents.