How many fruit smoothie are possible from 6 choices of fruits, 4 choices of milk, and 3 sizes

The best way to solve this is multiplication

start from the end

for every choice of milk, you can choose 3  sizes, therefore that's 12 alone

those 12 can apply to every 6 choices of fruit so multiply 6 by 12
which is 72

there are 72 possible outcomes for smoothie choices

Check the internet ok that will

The answer to your question is b