B. One
because an independent variable is something you change. So in a scientific experiment you only change one thing. If you happen to change more than one thing then the test becomes unfair therefore you should repeat and make sure that only one thing is changed this time.
Its not C. i took he test and got A.
Answer:No
Explanation:Plants will not just have to rely on one animal to help reproduce. Plants can mimic things such as scents or looks to be an incentive for other animals. Wind and water can also help transport pollen. Plants always have pollinators such as wind, water, insects, and animals. Plants use mimicry in order to attract the biotic pollinators. Plants will never have trouble reproducing because they have so many different pollinators.
The main reason why the testes are suspended within the scrotum is to provide cooler temperature for the testes and make it fertile for penetrating the egg. The Scrotum may contract or lengthen depending on the temperature of its surrounding.