Answer : Photosynthesis is an example of a chemical reaction.
Explanation :
Photosynthesis : It is a type of chemical process which takes place in the plant cell. In photosynthesis process, the light energy converted into the chemical energy.
As plant needs carbon dioxide, water and light. During the photosynthesis, carbon dioxide, water and sunlight react to gives glucose, oxygen and water as a product.
The balanced reaction of photosynthesis will be,

Hence, photosynthesis is an example of a chemical reaction.
The correct option is D.
A virus refers to an infectious micro organism that is made up of nucleic acid molecule that is enclosed within a protein coat. Viruses are only able to reproduce and multiply when they come in contact with living cells, in the absence of living cells they remain dormant and they do not show any sign of been a living thing. The nuclei acid molecule of a virus can be in form of a DNA molecule or a RNA molecule.
A- uracil, test prep question
Answer:
D. Population genetics
Population genetics is the study of genetic variation within populations, and involves the examination and modelling of changes in the frequencies of genes and alleles in populations over space and time. ... In natural populations, however, the genetic composition of a population's gene pool may change over time.
Explanation:
microevolution - evolutionary change within a species or small group of organisms, especially over a short period. (Not studying the overall evolution in the population, just a single allele usually) Not it then
macroevolution - Macroevolution in the modern sense is evolution that is guided by selection among interspecific variation, as opposed to selection among intraspecific variation in microevolution (this goes over huge groups of different species) Not it then
gene pool - The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species. (Not the study of evolution in a population) Not that then
So it has to be D
Pollution is the biggest impact as well as deforestation