Answer the following question given this paragraph: 

When a blood vessel gets clogged, there is no medical equivalent of "Drano" that will clear it out. There is, however, a procedure known as angioplasty. A thin tube with a balloon is threaded through the blood vessels. Once in place, the balloon is inflated to compress the clog against the artery wall.


Q: The procedure known as angioplasty is used when what part of the circulatory system is clogged?

 Choices:

- lungs

- the heart

- the spinal cord

- blood vessel

A:
blood vessel
