The correct answer is Choice C.
Substitute $r=1,250$ into the given function to find the total cost to rent a room for 12 months.
Choice A is incorrect and may result from finding $2,500+1,250$ which covers only a month worth of rent, not 12 months.
Choice B is incorrect and may result from finding $2,500+10\times1,250$ which covers only 10 months’ worth of rent, not 12 months.
Choice D is incorrect and may result from mistaking $2,500$ as the monthly rent, while using$1,250$ as the deposit.
✨ Expert's Tip ✨
Another method is to plot the function on a graph and read the value of the function when $r=1,250$.