I believe it is idiopathic.
The best and most correct answer among the choices provided by the question is the second choice or letter B "<span>OIs are more frequent in the earlier stages of HIV. "</span><span>
</span> Infections<span> that take advantage of weakness in the immune defenses are called “</span>opportunistic.” The phrase “opportunistic infection” is often shortened to “OI<span>.”</span>
I hope my answer has come to your help. God bless and have a nice day ahead!
Your question isn't the most clear, but I think your answer is rocks, or more specifically phosphorous rich rocks because the phosphorous will mix with the sediments on the river's/lake's ground forming phosphorous rich rocks.
That means that It'll become a phosphate mineral and later become phosphorous again when the minerals weather.
Hope it helped,
BioTeacher101