2171 (last digit 1) -> 1^n=1
2172 (last digit 2) -> 2 repeats its last digits as : 2,4,8,6,2..... => 9=4+4+1 => last digit = 2
2173 (last digit 3) -> 3 repeats its last digits as : 3,9,7,1,3..... => 11=4+4+3 => last digit = 7
2174 (last digit 4) -> 4 repeats its last digits as : 4,6,4..... => 13=2*6 + 1 => last digit = 4
1 + 2 + 7 + 4 =14
Answer : b