Punnett Square was developed by:

The correct answer is Option (3) → Reginald C. Punnett

The Punnett square is a grid that shows all the possible gametes of the two parents on its sides and all the possible offspring genotypes in its boxes. It is used to work out the probability of each genotype in a cross.

Option (1) Gregor Mendel — Incorrect. Mendel did the pea crosses and gave the laws of inheritance, but the square came later.

Option (2) Gregor Punnett — Incorrect. This mixes Mendel’s first name with Punnett’s surname; there is no such scientist.

Option (3) Reginald C. Punnett — Correct. The Punnett square, a graphical way to work out the possible genotypes of a cross, was developed by the British geneticist Reginald C. Punnett.

Option (4) Matthew Meselson Punnett — Incorrect. Matthew Meselson, with Franklin Stahl, proved semi-conservative replication of DNA. The name is mixed with Punnett’s.

NCERT Extract:
Inheritance of One Gene – “… The production of gametes by the parents, the formation of the zygotes, the F1 and F2 plants can be understood from a diagram called Punnett Square as shown in Figure 4.4. It was developed by a British geneticist, Reginald C. Punnett.”

Figure 4.4 A Punnett square used to understand a typical monohybrid cross conducted by Mendel between true-breeding tall plants and true-breeding dwarf plants