Biomolecues are essential to all living things. Which biomolecule is "B" from the above table?

I think the answer is Lipids because lipids contain the elements hydrogen, oxygen, carbon, and sometimes nitrogen and phosphorus.

The living matter is composed of mainly six elements - carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. These elements together constitute about 90% of the dry weight of the human body. Several other functionally important elements are also found in the cells. These include Ca, K, Na, CI, Mg, Fe, Cu, Co, I, Zn, F, Mo, and Se. Carbon is the most predominant and versatile element of life. It possesses a unique property to form an infinite number of compounds. This is attributed to the ability of carbon to form stable covalent bonds and C-C chains of unlimited length. It is estimated that about 90% of compounds found in living system invariably contain carbon. Life is composed of lifeless chemical molecules. A single cell of the bacterium, Escherichia coli contains about 6,000 different organic compounds. It is believed that man may contain about 100,000 different types of molecules although only a few of them have been characterized.