Given,

First term = a

Common ratio = r

We know that,

T_n = ar^{(n - 1)}

The product of first five terms of a G.P.

P = a × ar × ar² × ar³ × ar⁴

= a⁵ × r^0+1+2+3+4

= a⁵.r¹⁰

Hence, option 3 is the correct option.