If crossing over and independent assortment ceased to occur,
a. genetic variation would decline rapidly, with sperm or ova having the same alleles.
b. sperm will always have the same alleles, but ova will always have different alleles.
c. ova will always have the same alleles, but sperm will always have different alleles.
d. sperm or ova would alternate between the types of alleles they will contain.

Genetic variation would decline rapidly, with sperm or ova having the same alleles.

Explanation:

Crossing over is the exchange of genetic material between the chromatids of homologous chromosomes. It results in the formation of recombinant chromatids that have new combinations of maternal and paternal alleles. The gametes with recombinant alleles impart genetic variations to the progeny.

Likewise, an independent assortment of homologous chromosomes to the opposite poles during anaphase I of meiosis I result in the packing of alleles of a gene independent of that of the other gene. Independent assortment produces some gametes with new gene combinations and the other with parental gene combinations.

If crossing over and independent assortment cease to occur, male and female gametes will have the same alleles due to the absence of any source of recombination and the genetic variation in the progeny would be reduced.  

Explanation:

The impact of humans

The Earth is the source of all the resources we need, such as metals, plastics and fuels. Humans are very successful living things. We compete with other organisms for many natural resources. These include:

land (for farms, buildings and roads)

water (for drinking, watering fields, and industry)

The world’s human population is increasing, and this means that we are using more resources all the time.

Population growth

The human population in the year 1800 was about 1 billion, and now it is more than 7 billion (more than 7,000,000,000).

Deforestation

Humans have been cutting down trees for thousands of years. We do this to clear land for farming and building, and for wood to use as a fuel or building material.

Forestry is sustainable as long as forests are allowed to replace themselves, or are replanted after felling, but often this is not done. The result is that the world’s forests are steadily shrinking.

The slideshow maps show the loss of forest across the world over the last 10,000 years:

Pollution

We produce waste whenever we make or transport objects and substance. Waste materials include:

household and industrial rubbish

chemicals from industrial processes

smoke from burning fuels

harmful gases from burning fuels

They damage the environment and are a waste of resources.

- i hope this helps