Question 1062069
{{{ sin(7pi/3) = sqrt(3)/2 }}}
{{{ arcsin(sqrt(3)/2) = pi/3 }}} radians

By convention, arcsin(x) is expressed as an angle between {{{-pi/2}}} and {{{+pi/2}}}, so as an angle in quadrants 1 or 4, where positive angles are measured counterclockwise from the positive x-axis.   Only if other information is given should the angle be expressed as being quadrant 2 or 3.   Also note that the angle {{{ pi/3 }}} aliases to {{{ 7pi/3}}} because the latter rotates {{{ 2pi + pi/3 }}} radians (one full circle is {{{ 2pi}}} radians, but that answer does not follow the convention.    So only B looks correct.