What of the following is incorrect about the chromosomal theory of inheritance ?

Options

A. It was proposed by Sutton and Boveri in 1902.
B. The pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried.
C. The behaviour of chromosomes was non - parallel to the behaviour of genes and used chromosome movement to explain Mendel's laws
D. Sutton united the knowledge of chromosomal segregation with Mendelian principles and celled it the chromosomal theory of inheritance .

Answer

To determine which statement is incorrect about the chromosomal theory of inheritance, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Identify the Origin of the Theory**:
- The chromosomal theory of inheritance was proposed by Walter Sutton and Theodore Boveri in 1902. This statement is correct.

2. **Understanding Chromosomal Pairing and Segregation**:
- The theory states that during meiosis, the pairing and separation of chromosomes lead to the segregation of the factors (genes) that carry inheritance. This statement is also correct.

3. **Mendel's Contribution**:
- Gregor Mendel's work on pea plants established the laws of inheritance, identifying that traits are controlled by factors (now known as genes). This is a correct statement as well.

4. **Relationship Between Chromosomes and Genes**:
- The behavior of chromosomes during cell division parallels the behavior of genes. This means that the way chromosomes segregate during meiosis is similar to how Mendel's factors segregate. This is correct.

5. **Incorrect Statement Identification**:
- The statement claiming that "the behavior of chromosomes was non-parallel to the behavior of genes" is incorrect. In fact, the behavior of chromosomes is parallel to the behavior of genes, as established by the chromosomal theory of inheritance.

6. **Final Confirmation**:
- The last statement about Sutton combining chromosomal segregation knowledge with Mendelian principles to formulate the chromosomal theory is correct.

### Conclusion:
The incorrect statement regarding the chromosomal theory of inheritance is that "the behavior of chromosomes was non-parallel to the behavior of genes."