Answer:
B. 

Explanation:
We have,
The first term of the series, 
 .
.
The common difference is given by, 
 i.e.
 i.e. 
 .
.
Since, the given series is an infinite series, then,
Sum of an infinite series = 

i.e. Sum the series = 

i.e. Sum the series = 

i.e. Sum the series = 

i.e. Sum the series = 

i.e. Sum the series = 

Thus, the sum of the series is 
 .
.