Nucleosome existence and structure was first proposed in 1974 by:

Options

A. William Asbury
B. Rosalind Franklin
C. Roger Kornberg
D. John Crick

Explanation

To solve the question regarding who first proposed the existence and structure of nucleosomes in 1974, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks about the scientist who proposed the existence and structure of nucleosomes in 1974.

2. **Identify Key Terms**: The key terms here are "nucleosome," "existence," "structure," and the year "1974."

3. **Review the Options**: The options provided are:
- A) William Asperbury
- B) Rosa Lind Franklin
- C) Roger Cornberg
- D) John Craig

4. **Recall Relevant Information**: Nucleosomes are fundamental units of chromatin, consisting of DNA wrapped around histone proteins. The discovery and proposal of their structure were significant in understanding DNA packaging in cells.

5. **Identify the Correct Scientist**:
- William Asperbury is not known for nucleosome research.
- Rosa Lind Franklin was a key figure in DNA structure but not specifically in nucleosome studies.
- John Craig is not associated with the discovery of nucleosomes.
- Roger Cornberg is known for his work on the structure of nucleosomes, and he proposed their existence in 1974.

6. **Conclude the Answer**: Based on the information gathered, the scientist who proposed the existence and structure of nucleosomes in 1974 is **C) Roger Cornberg**.

### Final Answer:
**C) Roger Cornberg**