Verify teh trigonometric equation of each option
Remember that
The trigonometric function must be satisfy the points on the graph
so
Verify
we have
looking at the grahp
Fo x=0, y=0
For x=pi, y=0
For x=-pi, y=0
Option A
For x=0
substitute
y=3
so
the option A is not the equation of the graph
Option B
For x=0
y=3
the option B is not the equation of the graph
Option C
For x=0
y=0 ----> is ok
For x=pi
y=0 ----> is ok
For x=-p1
y=0 -----> is ok
the option C satisfy the given points
Option D
For x=0
y=1/2
the option D is not the equation
therefore
