The lock and key model was proposed by?

Explanation

The correct answer is Emil Fischer, who proposed the lock and key model, which describes how enzymes are specifically shaped to fit substrates, like a key fitting into a lock. This model emphasizes the specificity of enzyme-substrate interactions.Option Koshland is incorrect as he developed the induced fit model, which differs from the lock and key concept by suggesting that the enzyme's structure can change upon substrate binding, allowing for a more flexible interaction.Options Watson and Crick and Rosalind Franklin are also incorrect, as their contributions were primarily focused on the structure of DNA, with no direct relation to enzyme action models.