Answer:
B. 
Step-by-step explanation:
We have,
The first term of the series,
.
The common difference is given by,
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
.