The elevation of a temporary benchmark was measured using three differential levelling surveys. These elevations were recorded as $66\mathrm{.}778$mASL$,66\mathrm{.}542$mASL$,$ and $66\mathrm{.}365$mASL$.$ Determine the precision of these measurements using standard surveying conventions. The true elevation of TBM can be the average of the three measurements.

$1/150$

$1/161$

$1/200$

$1/100$