A light spring balance hangs from the hook of the other light spring balance and a block of mass M kg hangs from the former one. Then the true statement about the scale reading is

Options

A. (a)Both the scales read M/2 kilogram each
B. (b)Both the scales read M kilogram each
C. (c)The scale of the lower one reads M kilogram and of the upper one zero
D. (d)The reading of the two scales can be anything but the sum of the reading will be M kilogram

Explanation

To solve the problem, we need to analyze the setup of the two spring balances and the block of mass \( M \) kg hanging from them.

### Step-by-Step Solution:

1. **Understanding the Setup**:
- We have two light spring balances. The first spring balance (let's call it Balance A) is hanging from a hook. The second spring balance (Balance B) is hanging from Balance A.
- A block of mass \( M \) kg is hanging from Balance B.

2. **Drawing the Diagram**:
- Draw a vertical line representing the hook.
- Below the hook, draw Balance A.
- Below Balance A, draw Balance B.
- Finally, below Balance B, draw the block of mass \( M \) kg.

3. **Analyzing Forces**:
- The block of mass \( M \) exerts a downward force due to gravity, which is \( F = M \cdot g \), where \( g \) is the acceleration due to gravity.
- Since Balance B is directly supporting the block, it will read the weight of the block, which is \( M \cdot g \).

4. **Reading of Balance B**:
- Balance B will show a reading of \( M \cdot g \) because it is measuring the weight of the block.

5. **Reading of Balance A**:
- Balance A supports Balance B and the block. Therefore, the force it experiences is the sum of the forces from Balance B and the weight of the block.
- Since Balance B reads \( M \cdot g \), Balance A will also read \( M \cdot g \) because it is only supporting the weight of Balance B and the block.

6. **Conclusion**:
- Both spring balances read the same value, which is \( M \cdot g \). Therefore, the true statement about the scale readings is that both scales read \( M \cdot g \).

### Final Answer:
Both spring balances read \( M \cdot g \).