Option 2. y = 3 cos Οx is the answer.
Step-by-step explanation:
If the function is in the standard form of y = acos(bx+c) Β or y = asin(bx+c)
Then period of the given function will be = 2Ο/b
1) For y = cos(x - Ο/2)
Therefore period of the function will be = 2Ο/1 = 2Ο
2) For y = 3cos Οx
Period = 2Ο/Ο = 2
Correct option.
3) y = 2 sin 3x
Period of the function = 2Ο/3
4). y = -4sin 2x
Period of the function = 2Ο/2 = Ο
So option 2 is the answer.