which expression represents the series

Answer:
The first option is the correct answer.
Step-by-step explanation:
The given series is :
1 + 5 + 25 + 125 + 625
We get ;
[tex]5^0=1[/tex]
[tex]5^1=5[/tex]
[tex]5^2=25[/tex]
[tex]5^3=125[/tex]
[tex]5^4=625[/tex]
We can see that the power/exponent is ranging from 0 to 4.
So, the first option is the right answer where 'i' goes from 0 to 4.