In decreasing magnitude which of the following is correct ?

Options

A. km, cm, m, mm
B. km, m, cm, mm
C. m, km, cm, mm
D. km, cm, mm, m

Answer

To solve the problem of arranging the units in decreasing magnitude, we need to understand the relationships between the different units of measurement. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Identify the Units**: The units we need to compare are kilometers (km), meters (m), centimeters (cm), and millimeters (mm).

2. **Convert Units to a Common Base**: To compare the units effectively, we can convert them into the smallest unit, which is millimeters (mm).
- 1 kilometer (km) = 1000 meters (m) = 1000 × 100 cm = 1000 × 100 × 10 mm = 1,000,000 mm
- 1 meter (m) = 100 cm = 100 × 10 mm = 1000 mm
- 1 centimeter (cm) = 10 mm
- 1 millimeter (mm) = 1 mm

3. **List the Values**:
- 1 km = 1,000,000 mm
- 1 m = 1000 mm
- 1 cm = 10 mm
- 1 mm = 1 mm

4. **Arrange in Decreasing Order**: Now that we have all the values in millimeters, we can arrange them from largest to smallest:
- 1 km (1,000,000 mm)
- 1 m (1000 mm)
- 1 cm (10 mm)
- 1 mm (1 mm)

5. **Final Answer**: The decreasing order of the units is:
- Kilometers (km) > Meters (m) > Centimeters (cm) > Millimeters (mm)

### Conclusion:
The correct order in decreasing magnitude is: **km > m > cm > mm**.