D) differences between species and their ancestors
This is because of the adaptive mechanism and mutations the organisms have to respond to. <span>Adaptation processes occur to help species survive and thrive in the ecological balance of life. Structural adaptations are physical features of an organism that adapted through time. An example of this are the bills of a bird and the fur of bears that they generally need for their survival; birds for hunting, and bears to protect them from low climate areas.</span>
Well, Euglena is in phylum Euglenophyta, and Paramecium is in phylum Ciliophora. You can verify that with a quick Google search.
<span>Does that sort of narrow it down? :)</span>
Offspring will be heterozygous expressing the dominant trait.
Hope this helps.