Answer:
<em>If crossing over did not occur there would be no diversity among organisms.</em>
Explanation:
Crossing over and independent assortment are the two phenomena of meiosis by which genetic and physical diversity occurs. If crossing over did not occur then there would not be changes in the physical features of children. No physical diversity would be produced. Children would have the same physical features as the parents. Each chromosome would be identical to one of the parents and hence there will be reduced variations.
With the choices given, the answer to the biology question presented above would be b. heavy metals such as mercury. Heavy metals contribute to soil pollution more than air pollution. The other choices are sources of air pollution. Thus, letter b is the answer.
