Answer and Explanation:
A gene is a section of DNA. The change in the sequence of the DNA is known as mutation.  Mutation always changes the sequence of the DNA. Sunlight can cause mutation. Sunlight produces structures named thymine dimers. Thymine dimers produce twist in the shape of DNA. These twists make DNA hard to copy, which can lead to mutation. It is essential to use sunscreen to block UVA and UVB rays to prevent thymine dimers from emerging in our cells. The US Food and Drug Agency recommends an SPF (sun protection factor) to defend against skin aging and skin cancer. X-ray radiation is a form used in x-rays. The energy level of the X-ray radiation is very high that can produce free radicals. Free radicals can steal electrons from DNA that can cause mutation. By using medical images, we can decrease exposure to X-rays. Less exposure to X-rays prevents mutation and also prevents the production of gene protein in other body parts.
 
        
             
        
        
        
Answer:
Species
Explanation:
Species is the most specific and basic taxonomic level of classification and also the basic unit of biodiversity. Species is defined as group of highly closely related organisms that mate or breed to produce fertile offspring. After species genus is specific, and mostly organisms names are identified by species names and genus names as in binomial nomenclature, all scientific names are derived from genus and species e.g. the scientific name of frog is <em>Rana tigrina, </em>here '<em>Rana</em>' is genus name that is always capitalized and '<em>tigrena</em>' is species name that starts with small letter but both are always written in italics or underlined.
 
        
             
        
        
        
Similarities: Natural Selection and Artificial Selection both result in the alteration of the gene pool. It can also change phenotypes of different species'.
Differences: Artificial Selection is when a specific trait is not wanted, and so it is not bred. 
For example, humans did not like how yellow peas looked. They liked the healthy looking green better. So, they killed the yellow peas, and bred the green peas with other green pea plants, and right now it is almost completely out of our gene pool.
Natural Selection is when something naturally occurs, such as a natural disaster, famine, plague, invasive species introduction. 
For example, if 10 camels lived in a desert, but one of them didn't have as good of a metabolism and stayed full longer, then that one would survive, while the others might not.
 
        
             
        
        
        
I don’t know f I am correct but I think it’s C...