Which of the following statements is true about mutation?

Analyze the question: We need to find the true statement about mutation.

Concept: A mutation is a sudden, heritable change in the genetic material (DNA or chromosomes) of an organism. It can occur in the genes (gene or point mutation) or in chromosome structure or number (chromosomal mutation). Because it changes the genetic makeup, the genotype is always involved. If the changed gene is expressed, the change can also show up in the phenotype.

Step-by-step evaluation:

• A. Phenotype is not involved: False. Many mutations alter the phenotype. Examples are albinism and sickle cell anaemia, where the altered gene changes the haemoglobin and the observable traits.
• B. Genotype is not involved: False. Mutation is a change in the genotype, so this is the opposite of the truth.
• C. Artificial induction is not possible: False. Mutations can be induced by mutagens such as X-rays, UV light, gamma rays, and chemicals like mustard gas and colchicine. Plant breeders use this to produce improved crop varieties.
• D. Genotype is involved: True. Mutation is a change in genes or chromosomes, which is the genotype.

Answer: The correct option is D.

Exam tip: Remember that mutation starts at the genotype (DNA level) and may or may not appear in the phenotype. When you see "not involved" or "not possible" in a statement about mutation, be suspicious. Mutation is a genetic change, and it can be induced by mutagens.