Final answer:
Solution B is composed mainly of water (H2O), as it is the solvent for the albumen forming a homogeneous mixture.
Step-by-step explanation:
The question is asking what Solution B consists of if it is a mixture of one part albumen and two parts water. Albumen is none of the chemical substances listed in the options; instead, it is a type of protein, such as those found in egg whites. The options given (H2O, H3O, H2SO4, H2CO3) are chemical compounds. Based on the description, Solution B is primarily composed of water (H2O), as it is the solvent in which the albumen (a solute) is dissolved to form a homogeneous mixture. Therefore, the correct choice from the given options would be a) H2O.