Step 1: Understanding the Concept
Lymph nodes lie in groups along lymph vessels. Examples are cervical (neck), axillary (armpit), inguinal (groin) and popliteal nodes.
Step 2: Location
Popliteal nodes lie in the popliteal fossa, the hollow at the back of the knee. They drain lymph from the leg and foot.
Step 3: Pulse point
The popliteal artery in the same area can be felt as a pulse point.
Final Answer:
The popliteal lymph nodes are situated in the knees.
\[ \boxed{\text{(D) }\text{knees}} \]