Correct Option: C. Mutation Detailed Explanation 1. Understanding Genetic Variation: Genetic variation refers to the differences in DNA sequences among individuals within a population. This variation is crucial for the process of evolution, as it provides the raw material upon which natural selection can act. Without genetic variation, a population cannot adapt to changing environments, which can lead to extinction. 2. Role of Mutation: Mutations are changes in the DNA sequence of an organism's genome. They can occur due to various factors, including errors during DNA replication, exposure to radiation, or chemical mutagens. Mutations can be classified into several types, including:

• Point mutations: Changes in a single nucleotide (e.g., A to G).
• Insertions and deletions: Addition or loss of nucleotides in the DNA sequence.
• Chromosomal mutations: Large-scale changes that affect the structure or number of chromosomes.

Mutations can introduce new alleles (variations of a gene) into a population, which can lead to new traits. If these traits confer some advantage in survival or reproduction, they may become more common in subsequent generations through the process of natural selection. 3. Why Other Options Are Incorrect or Weaker:

• A. Natural Selection:
• While natural selection is a critical mechanism of evolution, it does not introduce new genetic variation. Instead, it acts on existing variation within a population. Natural selection favors individuals with advantageous traits, leading to an increase in those traits over time. However, it relies on the genetic variation that mutations have already provided.
• B. Genetic Drift:
• Genetic drift is a mechanism that causes random changes in allele frequencies in a population, particularly in small populations. While it can lead to the loss of genetic variation or fixation of certain alleles, it does not create new genetic variation. Instead, it is a process that can affect the distribution of existing genetic variation.
• D. Migration:
• Migration (or gene flow) involves the movement of individuals and their genetic material between populations. While migration can introduce new alleles into a population, it does not create new genetic variation. Instead, it redistributes existing genetic variation from one population to another.

Summary of Key Points

• Genetic variation is essential for evolution and adaptation.
• Mutations are the primary source of new genetic variation in a population.
• Natural selection, genetic drift, and migration do not create new genetic variation; they act on existing variation.
• Understanding the mechanisms of genetic variation is crucial for studying evolution and population dynamics.

Revision Summary

• Genetic variation is vital for evolution and adaptation.
• Mutations introduce new alleles and traits into a population.
• Natural selection, genetic drift, and migration act on existing variation, not create it.
• Recognizing the role of mutations helps in understanding evolutionary processes.