From the graph it is clear that this is a sine function, and not a cosine function. Sine at x = 0 is also 0, but cosine is 1.
So, options can be either a or b
But we also see that the sine is translated upwards. Note that when the sine sould be 0, the function takes value 3. This means that you have to add 3 to each 'y' valude of the function.
Therefore, the answer is b. y = sin(x) + 3
