Smallest parasitic flowering plant is
(a) Arceuthabium
(b) Rafflesia
(c) Balanophora
(d) Cistanche

Options

A. Arceuthabium
B. Rafflesia
C. Balanophora
D. Cistanche

Answer

To determine the smallest parasitic flowering plant from the given options, we can analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the smallest parasitic flowering plant among the given options. We need to evaluate each option based on their size.

2. **Option A: Arceuthobium**:
- Arceuthobium, commonly known as dwarf mistletoe, is a type of parasitic plant.
- It has a length of about 5 to 8 millimeters.
- This makes it one of the smallest known parasitic angiosperms.

3. **Option B: Rafflesia**:
- Rafflesia is known for having the largest flower among flowering plants.
- It is a parasitic plant but is not small; in fact, it is quite large.
- Therefore, Rafflesia cannot be the smallest parasitic flowering plant.

4. **Option C: Balanophora**:
- Balanophora is also a parasitic plant but has a length of around 30 millimeters.
- This size is larger than Arceuthobium, so it cannot be the correct answer.

5. **Option D: Cistanche**:
- Cistanche is a holoparasitic plant with a length ranging from 20 to 100 millimeters.
- This size is also larger than Arceuthobium, ruling it out as the smallest parasitic flowering plant.

6. **Conclusion**: After evaluating all the options, Arceuthobium stands out as the smallest parasitic flowering plant with a size of 5 to 8 millimeters.

### Final Answer:
The smallest parasitic flowering plant is **(a) Arceuthobium**.