**Question:** All the following features are true about umbilical cord except

A. The umbilical cord is a thin, flexible tube connecting the fetus to the placenta during pregnancy.
B. The umbilical cord contains only one blood vessel, the umbilical artery.
C. The umbilical cord is a thick, solid structure that provides support to the fetus.
D. The umbilical cord carries waste products from the fetus to the placenta for removal from the maternal circulation.

**Correct Answer:** **Option C:** The umbilical cord is a thick, solid structure that provides support to the fetus.

**Core Concept:** The umbilical cord plays a crucial role in the exchange of gases, nutrients, and waste products between the mother and the fetus during pregnancy. It is a thin, flexible tube consisting of three components: the umbilical artery, the umbilical vein, and the Wharton's jelly.

**Why the Correct Answer is Right:** While all other options are true, option C describes the umbilical cord as a thick, solid structure, which is incorrect. In reality, the umbilical cord is relatively thin and flexible, allowing it to move freely within the uterus. The umbilical cord is composed of blood vessels (umbilical artery and vein) surrounded by Wharton's jelly, which provides support, strength, and elasticity.

**Why Each Wrong Option is Incorrect:**

**A:** The umbilical cord is indeed a thin, flexible tube connecting the fetus to the placenta, but it carries both blood vessels (umbilical artery and vein) and Wharton's jelly, not just one blood vessel (option B). The umbilical cord facilitates the exchange of gases, nutrients, and waste products between the mother and the fetus.

**B:** The umbilical artery carries deoxygenated blood from the fetus to the placenta for exchange, then returns oxygenated blood back to the fetus. This option is incorrect because the umbilical artery is one of the two blood vessels in the umbilical cord, not the only one (option A).

**C:** This option inaccurately describes the umbilical cord as a thick, solid structure, which is not the case. As mentioned earlier, the umbilical cord is thin and flexible (options A and B), and it contains the umbilical artery, vein, and Wharton's jelly.

**D:** The umbilical cord transports waste products from the fetus to the placenta for removal, but this option emphasizes the solid structure aspect (option C) rather than its primary function.

**Why the Correct Answer is Right:**

The umbilical cord is a thin, flexible structure connecting the fetus to the placenta. Its primary function is to facilitate the exchange of gases, nutrients, and waste products between the mother and fetus, ensuring the fetus receives essential substances while eliminating waste.

**Why Each Wrong Option is Incorrect:**

**A:** The umbilical artery carries deoxygenated blood from the fetus to the