Gary has a collection of stamps. he tracks the number of stamps he collects every week. if x represents the number of weeks since he starts tracking and y represents the total number of stamps in his collection, which of the following situations is represented by the graph below?

a. gary initially has 40 stamps. he collects 20 stamps every week.
b. gary initially has 40 stamps. he collects 15 stamps every week.
c. gary initially has 40 stamps. he collects 5 stamps every week.
d. gary initially has 40 stamps. he collects 60 stamps every week.