Answer:
B: y=sinx
Explanation:
the parent sine function is a repeating function that goes from 0 to 1, with sin(0)=0 sin(pi/2)=1 sin(pi)=0 sin(3pi/2)=-1 and sin(2pi)=0, π≈3.1415926 and we see on this graph that the graph matches at all these major points.
the cosine parent function is essentially the same thing but shifted to the left by π/2. It is essential to familiarize yourself with the unit circle and the key angles and their respective sin and cosine values.