Answer
See graph below.
Work Step by Step
For $y=a\sin c(x−h) + k$ $y =a \cos c(x−h) + k$,
Amplitude: $|a|$, Period: $\frac{2\pi} {|c|}$,
Horizontal Shift: h
The question asks for a graph with an appropriate viewing rectangle, so we must calculate the period and then add it to the horizontal shift
Given $f(x) = \cos \frac{x}{80}$
The Amplitude is $|1| =1$
The Period is $\frac{2\pi}{|\frac{1}{80}|} = 160 \pi$
The Horizontal shift is 0 units to the right
The appropriate viewing rectangle would be from $[0, 160 \pi]$
See graph below.