Which function's graph has a period of 2

Given that the function is:

y=a cos( bx+c), or y=a sin(x+c)

then the period is calculated as T= 2π/b and if T=2:

2=2π/b

b=2π/2=π

Therefore, the correct answer is option B, y=3 cos πx.

Hope this answers the question. Have a nice day.

36 is the final answer! : )

is only a line? i think so