Chromosomal theory of sex determination was proposed by:

Options

A. EB Wilson and Stevens
B. Henking
C. McClung
D. Mendel

Explanation

To answer the question "Chromosomal theory of sex determination was proposed by:", we can follow these steps:

1. **Identify the Options**: The options provided are:
- A) E.B. Wilson and Stravon
- B) H.H.H. (Hermann Henking)
- C) M.C. Klang
- D) M.Dal

2. **Recall the Chromosomal Theory of Sex Determination**: The chromosomal theory of sex determination states that the sex of an organism is determined by its chromosomes. This theory was proposed by scientists who studied the role of chromosomes in determining sex.

3. **Research the Correct Scientist**: Among the options, H.H.H. (Hermann Henking) is known for his work related to sex determination in insects, particularly in his studies of the chromosomes in the fruit fly (Drosophila). He proposed that sex is determined by specific chromosomes.

4. **Select the Correct Answer**: Based on the information, the correct answer to the question is:
- B) H.H.H. (Hermann Henking)

5. **Conclusion**: The chromosomal theory of sex determination was proposed by Hermann Henking, who demonstrated that certain chromosomes are responsible for determining the sex of an organism.