Organic Chemistry involves the study of the reactions and properties of carbon-containing compounds. Carbon can form a vast number of compounds due to its unique bonding properties. In this question, we are given the reaction of CO with ethyl magnesium bromide.

Reaction of CO with Ethyl Magnesium Bromide:

CO (Carbon Monoxide) is a colorless, odorless, and toxic gas. It is a weakly acidic oxide of carbon that reacts with many compounds to form a variety of useful products. Ethyl magnesium bromide is an organometallic compound that is commonly used in organic synthesis. It is a strong nucleophile and can react with many carbonyl compounds.

The reaction of CO with Ethyl magnesium bromide proceeds as follows:

CO + EtMgBr → EtCOOMgBr

In this reaction, CO acts as an electrophile and is attacked by the nucleophilic carbon atom of the EtMgBr. The resulting intermediate, EtCOOMgBr, is a magnesium salt of acetic acid. This intermediate can be hydrolyzed to form acetic acid.

Hydrolysis of EtCOOMgBr:

EtCOOMgBr + H2O → EtCOOH + MgBrOH

In this step, the magnesium salt of acetic acid is treated with water to form acetic acid and magnesium hydroxide. Acetic acid is a colorless liquid with a pungent odor. It is a weak organic acid that can be used as a solvent, food preservative, and in the manufacture of various chemicals.

Therefore, the correct answer to this question is option B, acetic acid.