Which of these statements about the evolutionary history of humans and chicken is supported by this

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

i'm pretty sure its b i might be wrong though!

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.