Cell shrinkage will be the answer
Id say b. you can rule out d because we know for sure the environment can effect u so that's out. same with c because the environment dousen't say oh Ur alurgec to pollen so their will be no pollen when your out. a would be a possible one but it douse not deter man every genetic trait. id go with b.
Are there multiple choices?
Organisms can be UNICELLULAR where they are composed of only 1 cell or they can be MULTICELLULAR where they are composed of many cells. The first organisms to appear on earth where single celled and they developed the ability to photosynthesize and make food from inorganic compounds. UNICELLULAR organisms such as bacteria predates complex organisms that are Multi cellular
