A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is `90s, 91s, 92s and 95s`. If the minimum division in the measuring clock is Is, then the reported mean time should be
Options:
(a) `(92 ±2)s`
(b) `(92 ±5)s`
(c) `(92 ± 1.8)s`
(d) `(92 ± 3)s`