Train D travels with a speed of 90 km/h from Delhi to Mumbai. Train M travels from Delhi to Mumbai with a speed of 100 km/h. At any particular time during this journey, which of the following statements is true?

Options

A. Trains D and M have the same velocity as they are travelling in the same direction.
B. Trains D and M have same velocity but different speed.
C. Trains D and M have different speeds and different velocities.
D. Can't say, as the given information is insufficient.

Explanation

To solve the question regarding the speeds and velocities of Train D and Train M, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Information:**
- Speed of Train D = 90 km/h
- Speed of Train M = 100 km/h
- Both trains are traveling from Delhi to Mumbai.

2. **Understand the Concepts:**
- **Speed** is a scalar quantity that refers to how fast an object is moving, regardless of its direction.
- **Velocity** is a vector quantity that refers to the speed of an object in a specific direction.

3. **Analyze the Statements:**
- **Statement 1:** Train D and Train M have the same velocity as they are traveling in the same direction.
- Since Train D and Train M have different speeds (90 km/h and 100 km/h), they cannot have the same velocity. This statement is false.

- **Statement 2:** Train D and Train M have the same velocity but different speeds.
- This is also incorrect because if they have different speeds, they cannot have the same velocity. This statement is false.

- **Statement 3:** Train D and Train M have different speeds and different velocities.
- Since Train D and Train M have different speeds (90 km/h and 100 km/h), they also have different velocities because they are moving in the same direction but at different rates. This statement is true.

4. **Conclusion:**
- The correct statement is that Train D and Train M have different speeds and different velocities.

### Final Answer:
The true statement is: Train D and Train M have different speeds and different velocities.