Which mutation occurs when one nucleotide base is replaced with another base

The correct answer is a substitution mutation.  

A mutation, which substitute’s one base for another, that is, a change in a solitary chemical letter like switching an A to a G is known as a substitution mutation. This kind of substitution can modify a codon to something, which encrypts a distinct amino acid and leads to a small modification in the generated protein.  

i'm sorry, but can you list the answers? i cannot with something i don't know the answers to

,

chris

oceans

indian ocean

pacific ocean

atlantic ocean

arctic ocean

southern ocean