Substitution is a type mutation ( permanent change in the genetic material of the organism) that is caused by the exchange of one base with another.
This can occur during the process of DNA replication when an incorrect base is added in the new DNA molecule and thus replacing the original base pair. This can result in formation of new amino acid ( that result in different protein) or it may form a truncated protein ( when stop codon is produced due to substitution).
The Richter scale is a way of giving the intensity of all earthquakes a numerical value. this allows the strengths of different earthquakes to be compared. Because of this, i think the best answer is D
