The organisms which do not have chlorophyll and are mostly heterotrophs are:

Options

A. bacteria
B. algae
C. viruses
D. fungi

Explanation

To solve the question regarding the organisms that do not have chlorophyll and are mostly heterotrophs, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: We need to identify organisms that lack chlorophyll and primarily obtain their nutrition from other sources (heterotrophs).

2. **Defining Heterotrophs**: Heterotrophs are organisms that cannot produce their own food and rely on other organisms for nutrition. This is crucial for our selection.

3. **Evaluating the Options**:
- **Option A: Bacteria**: Some bacteria can perform photosynthesis (e.g., green bacteria), so they may not fit the criteria of lacking chlorophyll.
- **Option B: Algae**: Algae contain chlorophyll and can perform photosynthesis, thus they are not heterotrophs.
- **Option C: Viruses**: Viruses are not classified as living organisms in the traditional sense and do not have a metabolism, so they do not fit as heterotrophs.
- **Option D: Fungi**: Fungi are known to be heterotrophic organisms. They do not have chlorophyll and obtain their nutrients through saprophytic nutrition, feeding on decayed organic matter.

4. **Conclusion**: Based on the evaluation, the correct answer is **D: Fungi**. They do not have chlorophyll and are primarily heterotrophs.

### Final Answer:
The organisms which do not have chlorophyll and are mostly heterotrophs are **Fungi**.