Which of these structures contains a male gametophyte? A pine life cycle. Each letter marks a definite structure of this cycle. Letter A marks a structure that gives rise to and contains female reproductive cells. Letter B marks a part of the inner structure of the ovule. Letter C marks a big cell in the ovule. Letter D marks a round structure in the outer layer of the integument. Letter E marks a small structure formed in a microsporangium. A B C D E

because they want 2 and yea

answer: b: experiments that showed that all cells are similar in how they metabolize and in their composition

explanation:

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.