Explanation:
I don't see the answer options.
but in line 3 this is simply done by multiplying to eliminate the fractions on the right side of the equations.
and so, since h = h, we get c×sin(B) = b×sin(C).
in the last line we divide both sides first by b and then by c and get
sin(B)/b = sin(C)/c
the law of sine ...