Aor b or c or d which expression? ?

option A

Step-by-step explanation:

Notice that you need to emulate the series: 1 + 5 + 25 + 125 + 625 (a five total term series)

with the indicated sums.

The first term in the your series (addition) has to be "1". This fact already gets rid of two of the suggested sums (B, and D) because their first term is .

So, now analyzing the options A and C, we notice that A has a sum from i=0 to 4 (which gives a total of five terms ao, a1, a2, a3, and a4, while option C has a total of six terms (from i = 0 to 5): a0, a1, a2, a3, a4, a5.

S, the obvious candidate is option A. So now evaluate the five terms corroborating that:

Therefore, option A is the answer