What is a major limitation of genetic screens, and how can conditional mutants help overcome this limitation?

• A. Lethal mutations prevent further study; conditional mutants allow study under specific conditions.
• B. Mutations are irreversible; conditional mutants allow reversible mutations.
• C. Mutations affect non-essential genes; conditional mutants focus on essential genes.
• D. Mutations are too random; conditional mutants provide targeted mutations.

Answer: (A)