Context: Read the passage. Then answer the question.

Fleas are small insects that can feed on the blood of mammals, including dogs. A flea uses its specialized mouth to pierce a dog's skin and suck the dog's blood. The flea can drink up to 15 times its body weight in blood each day!
When the flea feeds on the dog's blood, the saliva from the flea's mouth can irritate the dog's skin. Sometimes the flea can also transmit, or pass, diseases to the dog.
Figure: a flea holding onto a dog's hair.
Which type of relationship is formed when a flea feeds on a dog's blood?
A. mutualistic
B. parasitic
C. commensal
Identify the correct option from the choices provided and respond with the letter of the correct option.

B