................ identified DNA as an acidic substance present in the nucleus of a cell

Options

A. Friedrich Meischer
B. Temin
C. Watson
D. William Harvey

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks for the identification of the scientist who recognized DNA as an acidic substance found in the nucleus of a cell.

2. **Reviewing Options:** The options provided are:
- A) Friedrich Meischer
- B) Tamin
- C) Watson
- D) William Harway

3. **Identifying the Scientist:**
- Friedrich Meischer was a Swiss physician known for his work on nucleic acids.
- He was the first to isolate nucleic acid from the nucleus of cells, which we now know as DNA.

4. **Historical Context:**
- Meischer conducted his experiments in the late 19th century and discovered that the substance he isolated was acidic in nature.
- He initially named the substance "nuclein" (later known as DNA) and noted its association with proteins.

5. **Conclusion:** Based on the historical contributions of the scientists listed, the correct answer to the question is:
- **A) Friedrich Meischer**