The cost for the raw materials of marble countertops, c, can be represented by the function c(a) = 4.25a, where a is the area of the countertops. The retail markup, m, can be represented by the function m(c) = 1.15c.

Substitute the raw-material cost c(a) = 4.25a into the markup function m(c) = 1.15c. This gives m(c(a)) = 1.15(4.25a) = 4.8875a, so the correct choice is A, m(c(a)) = 4.8875a.

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