Lionel's Lawn Care Is a Company That Maintains Residential Yards

Lionel's Lawn Care is a company that maintains residential yards.Lionel's cost for his standard package of mowing,edging,and trimming is $15,and he charges $25 for this service.For a total price of $40,Lionel will also trim shrubs,a service that adds an additional $10 to the total cost of the standard package.What is Lionel's marginal cost of adding the shrub-trimming service to the standard package?

A) $10
B) $15
C) $25
D) $40