SSC JE Mechanical Engineering 27 Oct 2020 Shift 2 Papers

Here, two alternate series are following:
Letter based series:
Z - 3 = W
W - 3 = T
T - 3 = Q
Q - 3 = N
N - 3 = K
Square of odd Number series:
${\left(1\right)}^2=1$
${\left(3\right)}^2=9$
${\left(5\right)}^2=25$
${\left(7\right)}^2=49$
${\left(9\right)}^2=81$
${\left(11\right)}^2=121$
Hence, N, 121 is correct.