The greatest contribution to genetic studies was made by

Step 1: Analyze the question The question asks who made the greatest contribution to genetic studies, which is the science of heredity and how traits pass from parents to offspring.

Step 2: Review each option

• A. Gregor Mendel: An Augustinian monk who experimented with garden pea plants (Pisum sativum). He discovered the basic laws of inheritance: the Law of Segregation and the Law of Independent Assortment. He also introduced the ideas of dominant and recessive factors (what we now call alleles). For this, he is called the "Father of Genetics."
• B. Thomas Hunt Morgan: Worked on fruit flies (Drosophila) and showed that genes are located on chromosomes (the chromosomal theory of inheritance), including sex linkage. This was important, but it built on Mendel's foundation.
• C. Charles Darwin: Proposed evolution by natural selection. His work is about evolution, not the mechanism of heredity.
• D. Robert Hooke: Discovered and named the cell by observing cork under a microscope. This is a contribution to cell biology, not genetics.

Step 3: Conclusion Mendel laid the foundation of genetics with his work on pea plants, so he made the greatest contribution to the field.

**Correct answer: A. Gregor Mendel.

Exam tip: Match the scientist to the keyword:

• Mendel → peas → heredity/genetics
• Morgan → fruit flies → chromosomes
• Darwin → natural selection → evolution
• Hooke → cork → cell