Compare the functions shown below in the attachment:
which function has the greatest maximum y-value?
f(x)
g(x)
h(x)
all three functions have the same maximum y-value.

In a graph, "y" axis is the vertical axis and the blue curve is your function "f(x)". So, on the blue curve, trace and mark the place that is the highest in the given window. Notice that when "x" axis (the horizontal one) is π, the blue curve reaches its highest point,
For h(x)=2cos(x)+1, remember that the maximum value for cos(x) is "1". So, the maximum value forh(x)=2(1)+1=3

I’d say letter a..