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.  

is in the form atp or adenosine triphosphate

i'm guessing this is from edg enuity so the answers would be, from top to bottom,

theodor schwann

matthias schleiden

robert hooke

rudolph virchow

anton van leeuwenhoek