Species endangered but with unknown cause is

Options

A. Rare
B. Vulnerable
C. Intermediate
D. Indeterminate

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a type of species that is endangered but has an unknown cause for its endangerment.

2. **Reviewing Options**:
- **Rare Species**: These are species that are not commonly found. They may not necessarily be endangered, and their endangerment may or may not have a known cause.
- **Vulnerable Species**: According to the IUCN Red List, these species are at risk of extinction in the near future. They are endangered, but the causes of their endangerment are often known.
- **Intermediate Species**: These species exhibit characteristics of both ancestors and descendants. They do not specifically relate to endangerment or unknown causes.
- **Indeterminate Species**: These species are indeed endangered, and the key characteristic is that the cause of their endangerment is unknown.

3. **Identifying the Correct Answer**: From the analysis of the options, the species that fits the description of being endangered with an unknown cause is the **Indeterminate Species**.

4. **Conclusion**: The correct answer to the question is **Indeterminate Species**.