Which of the following is not a plastid ?

Options

A. Chloroplast
B. Chromoplast
C. Leucoplast
D. Ribosome

Explanation

To determine which of the following options is not a plastid, we need to analyze each option provided:

1. **Chloroplast**:
- Chloroplasts are a type of plastid found in plant cells. They are primarily responsible for photosynthesis, the process by which plants convert light energy into chemical energy. Therefore, this option is a plastid.

2. **Chromoplast**:
- Chromoplasts are another type of plastid. They are responsible for the pigmentation in flowers and fruits, giving them their various colors. Thus, this option is also a plastid.

3. **Leucoplast**:
- Leucoplasts are yet another type of plastid. Their main function is to store food, such as starches, oils, and proteins. Hence, this option is also a plastid.

4. **Ribosome**:
- Ribosomes are not plastids; they are cell organelles responsible for synthesizing proteins. They play a crucial role in translating messenger RNA into polypeptide chains, which then fold into functional proteins. Therefore, this option is not a plastid.

Based on the analysis, the answer to the question "Which of the following is not a plastid?" is **D. Ribosome**.