2021 AMC 12A Problem 4

Tom has a collection of 13 snakes, 4 of which are purple and 5 of which are happy. He observes that

- all of his happy snakes can add,

- none of his purple snakes can subtract, and

- all of his snakes that can't subtract also can't add.

Which of these conclusions can be drawn about Tom's snakes?

\textbf{(A) } Purple snakes can add.

\textbf{(B) } Purple snakes are happy.

\textbf{(C) } Snakes that can add are purple.

\textbf{(D) } Happy snakes are not purple.

\textbf{(E) } Happy snakes can't subtract.

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.