I think it’s because the bacteria has evolved and become immune to the antibiotics.
Answer - <span>C) Trees and shrubs provide shade, which keeps the water temperature cooler. Lower temperatures allow the water to hold more oxygen, which in turn creates a healthier habitat for the trout.</span>
Reasoning - The back story is if the water temperature is being changed. It will affect the trout indirectly warming the water. In turn if you have shades and shrubs to provide it for cooler areas it will preserve O2 a Certain Habitat for the Species.
It is intended to increase immunity against that antigen back to protective levels, after memory against that antigen has declined through time.
<span>environmental protection agency</span>