There are many different types of warts. Some occur on feet and fingers; others, like these filiform warts, normally occur on the face and neck. Regardless of the type, warts are caused by

Explanation:

common warts are actually an infection in the top layer of skin, caused by viruses in the human papillomavirus, or HPV, family. When the virus invades this outer layer of skin, usually through a tiny scratch, it causes rapid growth of cells on the outer layer of skin – creating the wart

the answer is "a.) well–developed vascular system."

explanation: