If g is the gallons of gas, and the truck holds up to 20 gallons, then g can be anything from 0 to 20.
If there is zero gallons of gas (g = 0) then the truck will travel zero miles because M(0) = 17(0) = 0.
The max miles depends on the max gallons of gas, so the miles possible with 20 gallons is M(20) = 17(20) = 340.
So, g ranges from 0 to 20 and M(g) ranges from 0 to 340.
Therefore your answer is the last option.
