Today Rose is twice as old as Sam and Sam is 3 years younger than Tina. If Rose, Sam, and Tina are alive 4 years from today, which of the following must be true on that day?

I. Rose is twice as old as Sam.
II. Sam is 3 years younger than Tina.
III. Rose is older than Tina.

A) I only
B) II only
C) III only
D) I and II
E) II and III

I am not looking for the answer. I am looking for the logic behind the answer. I read the logic in the OG, and everything is clear to me until the very last bit.