D — this is the nature vs. nurture debate
The correct answer is The effect of oil spills on marine animals.
Environmental scientists deals with the study of nature and the interaction of nature with other organisms. Any effect on environment caused by any means is studied by environmental scientist.The effect of oil spills is harmful on marine animals and this is known to us because it was studied by the environmental scientists. This is also apart of environmental science.
The right answer is B) crossing over.
Crossing-over is a genetic phenomenon that occurs during meiosis and contributes to genetic mixing during reproduction (genetic recombination).
At the end of prophase 1 (early metaphase 1) of meiosis, the homologous chromosomes (i.e. of the same pair) overlap thus forming characteristic features called "chromatid tetrads" and exchange fragments of chromatids. The result is the intra-chromosomal mixing of the alleles
