Answer:
Gene flow
Explanation:
Evolution is the changes seen in the growth, development, features of a certain group of species during the cause of time. Evolution causes changes in the gene frequency of species from one generation to the next generation. 
There are 5 important mechanisms of evolution and they are: Gene flow, mutation, genetic drift, natural selection and non random mating.
Gene flow as a mechanism of evolution is the exchange or transfer of genes between a group of species as they move from one place to another. Gene flow can either increase the rate of evolution or decrease it.
 
        
             
        
        
        
Answer:
Petroleum gas is mainly C3 and C4 based (propane and butane), whilst natural gas is predominantly C1 and C2 (methane and ethane). Petroleum gas is generally produced via the cracking of naphtha, which is one of the components separated during crude oil refining.
Explanation:
 
        
             
        
        
        
The answer is continental rise that is what I found!!!!! I hope this helps!!!!!!