Read the following context and choose the best option to answer the question.
Context: My right arm has been starting to worry me . It has recently begun to have a strange sensation in on of my veins . It feels as though my blood has turned into a thick substance with a million ants in it . When my arm points up , I can feel my blood & what seems to be ants rushing slowly down my arm .
Question: Why is the narrator worried about their arm ?
Options: 
A. They get a strange feeling when pointing their arm down .
B. They are getting no feeling .
C. They feel that the blood is pumping too fast .
D. They feel possible blood clots .


D