<span>Atherosclerosis is a common cause, because there is a lack of blood flow in the person's body, and this can cause a male to be impotent.
Diabetes is also a common cause because once again it causes less blood flow.
In a younger man, a cause could be anxiety. This is because nervousness and being anxious can lessen blood flow.
If you have choices, I suggest choosing one that has to do with less blood flow happening, which that is the main cause.
I hope that this could possibly help you with your studies, and have an amazing day. If you have any more questions, send me a pm. </span>
B. How far do butterflies migrate
A, C and D are opinions not facts.
I am going to assume you meant the "first trophic level" of the ecosystem. The first tropic level of an ecosystem is made up of producers, so the answer is C, Acorns.
<span>B. The food supply diminishes in all socioeconmic classes.</span>
That would be called <span>Defecation.</span>
