Context: Read the passage. Then answer the question.

A rat tapeworm is a type of flatworm that can live inside a rat's body. When a rat eats an insect that has a tapeworm inside it, the insect is digested, but the tapeworm remains alive.
The tapeworm is moved into the rat's intestines and uses suckers to attach itself to the intestine wall. Inside the rat's intestine, the tapeworm absorbs nutrients from food that the rat has eaten. If the rat has many tapeworms in its intestines, it will become weak from lack of nutrients.
Figure: a tapeworm attached to the wall of an intestine.
Which type of relationship is formed when a rat tapeworm attaches itself to a rat's intestine?
A. parasitic
B. mutualistic
C. commensal
Select the correct answer from the provided options and reply with the letter associated with it.
Answer: A