I believe it is D. More African elephants today naturally lack tusks compared to the elephant populations 100 years ago, because big game hunters sought elephants for ivory.
Answer and Explanation: The figure below shows the doses of BPA administered to the female mice over time.
An experiment is used to determine cause and effect among variables. When the research is for the impact of a treatment, researchers randomly separate individuals in two groups:
- <em><u>Control</u></em> <em><u>Group</u></em> doesn't receive any treament or a placebo or a treatment whose outcome is already known;
- <em><u>Treatment</u></em> <em><u>Group</u></em> receives the treatment;
For the female mice on the image below, in the First Group is not injected any dosage of BPA, so they are the control group, while the <u>others</u> are <u>treatment group</u>.
The variables in a experiment are classified as independents or dependents:
- <em><u>Independent</u></em> <em><u>Variable</u></em> is the cause;
- <em><u>Dependent</u></em> <em><u>Variable</u></em> is the effect;
For the BPA research, since it is the effect of BPA over time on the mice's cells it is being investigated, <u>dosage</u> of BPA is the <u>independent</u> variable and <em>time</em> is the <em>dependent</em> variable.
A C - only male expressed the disorder and only females carried the disease. This is typical of a special type of diseases where only females are and can be carriers and only men can and are affected. There aren't many diseases like this but they do exist.
It is called the Rugae.
Rugae is a term used in anatomy to refer to a series of ridges produced by folding of the wall of an organ. For example the gastric rugae which allows for expansion of the stomach after the consumption of foods and drinks. The rugae of the vagina are the transverse ridges on the mucous membrane lining the vagina. They allow the vagina to stretch during childbirth.