Mendel published his work on inheritance of characters in 1865, but it remained unrecognised till 1900 due to the reason (s)
(A) Communication was not easy in those days.
(B) His contemporaries did not accept factors as discrete units of heredity.
(C) Mathematical approach to explain inheritance was totally new.
(D) Mendel could not provide any physical proof for the existence of factors

Options

A. Only A and B are correct
B. Only B and C are correct
C. Only C and D are correct
D. All are correct.

Answer

To solve the question regarding why Mendel's work on inheritance remained unrecognized until 1900, we can analyze each of the provided options step by step.

### Step 1: Evaluate Option (A)
**Option (A): Communication was not easy in those days.**
- In the 19th century, communication methods were limited. Scientific journals were not as widespread, and the sharing of research findings was slow. This could have contributed to the lack of recognition of Mendel's work.

### Step 2: Evaluate Option (B)
**Option (B): His contemporaries did not accept factors as discrete units of heredity.**
- Mendel introduced the concept of "factors" (now known as genes) as discrete units of heredity. At that time, many scientists were not ready to accept this idea, as the prevailing theories of inheritance were different. This lack of acceptance could have hindered the recognition of his work.

### Step 3: Evaluate Option (C)
**Option (C): Mathematical approach to explain inheritance was totally new.**
- Mendel used a mathematical approach to analyze inheritance patterns, which was quite innovative for his time. While this method was groundbreaking, it may have also made it difficult for some contemporaries to understand and accept his findings.

### Step 4: Evaluate Option (D)
**Option (D): Mendel could not provide any physical proof for the existence of factors.**
- Mendel's work was primarily theoretical, and he did not have the technology or knowledge to provide physical evidence of the existence of genes. This lack of empirical proof could have contributed to the skepticism surrounding his findings.

### Conclusion
Based on the evaluation of each option, it is clear that multiple factors contributed to the unrecognized status of Mendel's work. Therefore, the correct answer includes all the options (A), (B), (C), and (D) as reasons for the lack of recognition until 1900.

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