Options B and D
The domain of a function is the values that can be input into the function and the range of a function is the possible outputs from the function. Since Wong can use up to 10 canisters, the domain would be all integers between 0 and 10 inclusive. And since he uses exactly 3 balls per contained, the range will be all integer multiples of 3 ranging from 0 to 30 inclusive. Examining the available options, only option "B" is correct about the range (you can't have fractional containers, so option A won't work). Option "D" is correct for the range.
