Question

which word part means \lymph vessel\?
adenoid/o
lymph/o
lymphaden/o
lymphangi/o

Explanation:

In medical - related word parts, "lymphangi/o" specifically refers to lymph vessel. "adenoid/o" relates to adenoids, "lymph/o" is a more general root for lymph, and "lymphaden/o" refers to lymph nodes.

Answer:

lymphangi/o