Fe, Mg and Co are present respectively, in

Options

A. haemoglobin, myoglobin and chlorophyll
B. haemoglobin, chlorophyll and vitamin `B_(12)`
C. chlorophyll, vitamin `B_(12)` and myoglobin
D. vitamin `B_(12)`, haemoglobin and chlorophyll

Explanation

To solve the question regarding the presence of Iron (Fe), Magnesium (Mg), and Cobalt (Co) in specific biological molecules, we can analyze each option provided:

1. **Identify the elements and their biological significance:**
- **Iron (Fe)**: Known to be an essential component of hemoglobin, which is responsible for transporting oxygen in the blood and gives blood its red color.
- **Magnesium (Mg)**: A key component of chlorophyll, the pigment responsible for photosynthesis in plants.
- **Cobalt (Co)**: Found in vitamin B12, which is crucial for red blood cell formation and neurological function.

2. **Analyze the options given:**
- **Option A**: Hemoglobin (Fe), Myoglobin (Mg), Chlorophyll (Co)
- Incorrect, as Myoglobin contains Iron, not Magnesium.
- **Option B**: Hemoglobin (Fe), Chlorophyll (Mg), Vitamin B12 (Co)
- Correct, as it matches the known associations: Hemoglobin contains Iron, Chlorophyll contains Magnesium, and Vitamin B12 contains Cobalt.
- **Option C**: Chlorophyll (Fe), Vitamin B12 (Mg), Myoglobin (Co)
- Incorrect, as Chlorophyll contains Magnesium, not Iron, and Vitamin B12 contains Cobalt, not Magnesium.
- **Option D**: Vitamin B12 (Fe), Hemoglobin (Mg), Chlorophyll (Co)
- Incorrect, as Vitamin B12 contains Cobalt, not Iron, and Hemoglobin contains Iron, not Magnesium.

3. **Conclusion:**
- The correct answer is **Option B**: Hemoglobin contains Iron, Chlorophyll contains Magnesium, and Vitamin B12 contains Cobalt.

### Step-by-Step Solution:
1. Identify the biological molecules associated with Iron, Magnesium, and Cobalt.
2. Analyze each option to see which elements correspond to the correct biological molecules.
3. Eliminate incorrect options based on the known associations.
4. Confirm that Option B is the only one that accurately reflects the presence of Iron in Hemoglobin, Magnesium in Chlorophyll, and Cobalt in Vitamin B12.