The number of integers between 300 and 1100 which are divisible by either 7 or 13 but not both is

Multiples of 7 are {301,308 ................................1099}
Using the Ap formula, we can get that 301+ (n-1)7 = 1099
Giving n=115, that is there are 115 numbers that multiples of 7 in the given range. 

Multiples of 13 are {312,323,.................................1092} n = 61

Multiples of 91 are {364,455.................................1092} n= 9

Number of integers which are divisible by either 7 or 13 but not both is 115+61-2*9

=158

Hence B is the correct answer.