In the classification of matter chart, letter b. would be a(n)
a) acid.
b) compound.
c) element.
d) solution.

The answer is B. Just had it on usatestprep  

The correct answer is Option B.

Explanation:

An acid is defined as the substance which has more number of protons in the solution.

A compound is defined as the substance which can be chemically broken down into simpler substances. It is considered as a pure substance.

An element is defined as a substance which cannot be broken down into simpler substances by any chemical means. It is considered as a pure substance.

A solution is defined as a mixture of solute and solvent in which solute particles are homogeneously distributed among the solvent particles.

Letter B corresponds to the compound. Hence, the correct answer is option B.