Select the wrongly matched option.

Options

A. (1) Nitrobacter - Chemoautotrph
B. (2) Anabaena - Autotroph
C. (3) Rhodospirillum - Symbiotic N2 -fixer
D. (4) Rhizobium - Heterotroph

Answer

To solve the question of selecting the wrongly matched option, we will analyze each option provided:

1. **Nitrobacter - Chemotrop**:
- Nitrobacter is a type of bacteria that oxidizes ammonia into nitrites and then into nitrates. This process allows it to derive energy from inorganic substances. Therefore, this match is correct.

2. **Autotrop - Prepare their own food from simple inorganic matter**:
- Autotrophs are organisms that can produce their own food through processes like photosynthesis or chemosynthesis, using simple inorganic substances. This match is also correct.

3. **Rhodospirillum - Symbiotic Nitrogen Fixer**:
- Rhodospirillum is a type of bacteria that is known to fix nitrogen, but it does so as a free-living organism, not in a symbiotic relationship with plants. Therefore, this match is incorrect.

4. **Rhizobium - Heterotroph**:
- Rhizobium is a genus of bacteria that forms symbiotic relationships with leguminous plants to fix nitrogen. However, it is not classified as a heterotroph; it is a symbiotic nitrogen fixer. This match is also incorrect.

After analyzing all options, the wrongly matched option is:

**C. Rhodospirillum - Symbiotic Nitrogen Fixer**

### Step-by-Step Solution:
1. Identify and analyze the first option: Nitrobacter is correctly matched as a chemotropic organism.
2. Analyze the second option: Autotrophs are indeed those that prepare their own food from inorganic matter, confirming this match is correct.
3. Examine the third option: Rhodospirillum is incorrectly matched as a symbiotic nitrogen fixer since it is a free-living nitrogen fixer.
4. Review the fourth option: Rhizobium is incorrectly labeled as a heterotroph; it is a symbiotic nitrogen fixer.
5. Conclude that the option that is wrongly matched is C: Rhodospirillum - Symbiotic Nitrogen Fixer.