Studies have shown that people spend more money in shopping areas with trees than in shopping areas without trees
Explain how this is a social or economic benefit of trees.

answer: d. load

a river's load refers to the natural phenomena in which the sediments, rocks   stones, boulders and other deposits are removed and picked from the bottom bed of the river due to the abrasion resulted by the high speed water current.

option d : from a warmer substance to a cooler substance

according to second law of thermodynamic, heat flows from higher to lower temperature region. heat is the transfer of energy from an object at higher temperature to an object at a lower temperature. so energy flows from warmer to colder objects.