The biologist who investigated the structure and function of chromosome was

The correct option is C

Thomas Morgan

The correct option is C.

Explanation of the correct option:

1. Chromosomes are a collection of thread-like structures that come in a variety of lengths and forms.
2. DNA and proteins make up chromosomes (mainly histones).
3. Genes are carried on chromosomes.
4. While working on the fruit fly named Drosophila melanogaster, Thomas H. Morgan was the first to explore the structure and functions of chromosomes.

Explanation of the incorrect options:

Option A: Walther Flemming originally discovered chromosomes in 1882 while studying cell division in salamander larvae.

Option B: Rosalind Franklin studied the nature and shape of DNA molecules in 1953.

Option D: The theory of natural selection was explored by Robert Darwin.

The biologist who investigated the structure and function of chromosomes was Thomas Morgan.