proportional relationships have constant ratios.
the graph is a line, so it is a proportional relationship. (A)
the function is in the form y=kx (proportional function) (C)
Find the ratio of the tables: (B)

D

All represent a proportional relationship
Infinite, because essentially the graph is going to have a horizontal line because f(x)=58/y=58 just means that the y will remain on 58 but the x can have whatever value.
If we assume the number of polo shirts have been sold is x, the number of casual shirts have been sold will be 4x.
x*18+4x*9=$1080
(18+36)x=$1080
54x=$1080
x=20
The number of casual shirts have been sold is 4*20=80