Can I please get an explanation for this answer?

Question 33 1 pts Answer the question on the basis of the following total utility data for products L and M. Assume that the prices of L and M are $3 and $4, respectively, and that the consumer's income is $18 Units of L Total Utility Units of M Total Utility 9 1 16 N 15 2 28 18 3 36 4 20 4 40 5 21 5 42 How many units of the two products will the rational consumer purchase? O 3 of L and none of M O 4 of L and 2 of M O 3 of L and 5 of M O 2 of L and 3 of M