The order of reactivity is

Options

A. `Al gt Mg gt Fe gt Zn`
B. `Mg gt Al gt Zn gt Fe `
C. `Al gt Mg gt Zn gt Fe `
D. `Mg gt Al gt Fe gt Zn`

Explanation

To determine the order of reactivity among the metals Aluminium, Magnesium, Ferrous (Iron), and Zinc, we can refer to the reactivity series of metals. The reactivity series ranks metals based on their ability to displace other metals from compounds and their tendency to react with water and acids.

### Step-by-Step Solution:

1. **Identify the Metals**: The metals given in the question are Aluminium (Al), Magnesium (Mg), Ferrous (Fe), and Zinc (Zn).

2. **Refer to the Reactivity Series**: The reactivity series lists metals in order of their reactivity. The order from most reactive to least reactive is:
- Potassium (K)
- Sodium (Na)
- Lithium (Li)
- Barium (Ba)
- Strontium (Sr)
- Calcium (Ca)
- Magnesium (Mg)
- Aluminium (Al)
- Manganese (Mn)
- Zinc (Zn)
- Chromium (Cr)
- Iron (Fe)

3. **Locate Each Metal in the Series**:
- Magnesium (Mg) is higher in the series than Aluminium (Al).
- Aluminium (Al) is above Zinc (Zn).
- Zinc (Zn) is above Ferrous (Fe).

4. **Determine the Order of Reactivity**: Based on their positions in the reactivity series, we can establish the order of reactivity:
- Magnesium (Mg) is the most reactive.
- Aluminium (Al) is next.
- Zinc (Zn) follows.
- Ferrous (Fe) is the least reactive.

5. **Write the Final Order**: The order of reactivity from highest to lowest is:
- Magnesium (Mg) > Aluminium (Al) > Zinc (Zn) > Ferrous (Fe)

### Final Answer:
The order of reactivity is:
**Magnesium > Aluminium > Zinc > Ferrous**