Which of the following is a difficulty associated with environmental protection?
a.
cost
b.
unpredictability
c.
sustainability
d.
all of the above

D. All the above

Explanation:

Unpredictability of the any event, the cost for a solution, and the sustainability of the solution are all factors which make it difficult with environmental protection.

it is a limiting nutrient limited by a single nutrient in the ecosystem, & the single goes very slow.

answer///triple meter;