Answer:
b. cell x because it has chloroplast.
A hypothesis is a testable possible explanation, while a theory is an explanation that has been tested extensively.
If you need to learn more and remember about this stuff better, watch the Amoeba Sister's <em>Casual and Scientific Use of "Theory" and "Law"</em>. Trust me, it helps!
:)I hope I answered your question well!:)
71 percent of this planet is covered by water, mostly because of our oceans.