Your answer would be... B. The climate on Earth has changed over time.
On May 14, 1796, Jenner<span> took fluid from a cowpox blister and scratched it into the skin of James Phipps, an eight-year-old boy. A single blister rose up on the spot, but James soon recovered. On July 1, </span>Jenner<span> inoculated the boy again, this time with smallpox matter, and no disease developed. The </span>vaccine<span> was a success.</span>
1.
Paramecium
2.
Amoeba
3.
Paramecium
4.
Euglena
5.
Volvox
6.
Amoeba?
7.
Amoeba
8.
Cilia
9.
Flagellum
10. Psuedopods
11. Flagella
12. Euglena
(Chloroplast)
13. Amoeba
14. Euglena
15. Paramecium
16. Paramecium
17. Amoeba
18. Volvox
I hope this is all correct!