Correct option is C
Given series: 49, 64, (...), 100, 121
These numbers can be expressed as squares of consecutive integers:
· 49 = 7²
· 64 = 8²
· 100 = 10²
· 121 = 11²
The missing number should fit between 828^282 and 10210^2102, which is 929^292:
· 81 = 9²
Thus, the missing number is: (c) 81