[tex]sine=\dfrac{opposite\ leg}{hypotenuse}\to\boxed{B}[/tex]
Other:
[tex]\dfrac{hypotenuse}{opposite\ leg}=cosecant\\\\\dfrac{opposite\ leg}{adjacent\ leg}=tangent\\\\\dfrac{adjacent\ leg}{hypotenuse}=cosine[/tex]
the opposite leg/hypotenuse=sine of an angle in a right triangle
