Answer: The correct option is (D). RF.
Step-by-step explanation: We are given to select the correct side that is included between the angles ∠R and ∠F in ΔFTR.
As shown in the attached figure, we have drawn triangle FTR.
Now, the side that is included between the angles ∠R and ∠F has endpoints at the vertices R and F.
So, we call that side as the side RF.
Therefore, the required side that is included between the angles ∠R and ∠F is the side RF.
Thus, (D) is the correct option.