The $1\mathrm{.}82$ m long string is observed to have the following standing wave when the standing wave has a frequency of $120$ Hz$.$ What is the wave speed?

Question $4$ options:

A$)$

$86\mathrm{.}5$ m$/$s

B$)$

$72\mathrm{.}8$ m$/$s

C$)$

$124$ m$/$s

D$)$

$69\mathrm{.}0$ m$/$s