A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90 s, 91 s, 95 s and 92 s. If the minimum division in the measuring clock is 1 s, then the reported mean time should be :

Question

( A ) $92 \pm 5.0 \;s$
( B ) $92 \pm 3\; s$
( C ) $92 \pm 1.8 \; s$
( D ) $92 \pm 2 \;s$