The correct option of this question is (a).

Since, a = \(\frac {v-u}{t}=\frac {v-0}{n}=\frac v n\)

Displacement in last 2s,

\(s _ { n } - s _ { n - 2 } = \frac { 1 } { 2 } a n ^ { 2 } - \frac { 1 } { 2 } a ( n - 2 ) ^ { 2 }\)

\(= 2 a ( n - 1 ) = 2 \times \frac { v } { n } ( n - 1 ) = \frac { 2 v ( n - 1 ) } { n }\)