Option 1: Identifying the molecular ruler in ribosomal assembly which ensures error-free synthesis of protein in cells.

This option suggests that Venkatraman Ramakrishnan was awarded the Nobel Prize for his contributions in identifying a molecular ruler in ribosomal assembly. This molecular ruler plays a crucial role in ensuring the error-free synthesis of proteins in cells. However, there is no information provided in the question or anywhere else about Venkatraman Ramakrishnan`s work related to a molecular ruler in ribosomal assembly. Therefore, this option is incorrect.

Option 2: Synthesizing a group of life-saving antibiotics.

This option implies that Venkatraman Ramakrishnan was awarded the Nobel Prize for synthesizing a group of life-saving antibiotics. However, there is no mention of Venkatraman Ramakrishnan`s work in antibiotic synthesis in the question or anywhere else. Thus, this option is incorrect.

Option 3: The work on green fluorescent protein of jellyfish.

This option suggests that Venkatraman Ramakrishnan`s Nobel Prize was awarded for his work on the green fluorescent protein of jellyfish. However, there is no reference to Venkatraman Ramakrishnan`s involvement in studying the green fluorescent protein of jellyfish