Answer: when looking at the graph, anything that is going down is decreasing and anything that is going up is increasing. Maybe that can help you.
Step-by-step explanation:
X=40 because you set all the degrees equal to 360 degrees because its a circle :)
The sinusoid makes a complete oscillation (i.e. 360°) every 3 seconds. So, in one second it makes 1/3 of a turn, leading to 360°/3 = 120°.
So, the correct answer is the last one.
