The 20^th term from the end of the A.P. 3, 8, 13, ..., 253 is:

158

The A.P. 3, 8, 13, ..., 253 is

here First Term = 3

Last or nth term of A.P. = 253

Common difference, d = 5

253 = 3 + (n-1)*5

n-1 = 250/5 = 50

n = 51 terms

Thus 20th term from the end is 32nd term

a(32) = 3 + (32-1)*5 = 3 + 31*5 = 158

The correct answer is Option (1) → 158