The Semi-fluid layer moves in circular movements based on the temperature and density of it's particles. When the particles become less dense, the semi-fluid rises. Once it reaches the bottom of the crust, the particles become dense, and go back to the inner core. Once it's at the inner core, the particles temperature heats up again and causes the circular movements to proceed.
Answer:
Mutation.
Explanation:
Mutation may be defined as the sudden heritable change in the DNA sequence of the organisms. Mutation can results in the change in the genotype and phenotype of the organisms.
Two main types of mutation are spontaneous mutation and induced mutation. Induced mutation occurs intentionally with the help of the mutagens. Spontaneous mutation is the natural mutation that occurs for the no known reason.
Thus, the answer is spontaneous mutation.
I believe the answer is d
