Which of the following plays an important role in the early-warning systems for cyclones?

Options

A. Helicopters
B. Submarines
C. Satellites
D. Stars

Explanation

To determine which of the following plays an important role in the early-warning systems for cyclones, we can analyze each option provided:

1. **Helicopter**: While helicopters can be used for various purposes, including search and rescue operations, they are not primarily used for monitoring weather patterns or providing early warnings for cyclones.

2. **Submarine**: Submarines operate underwater and are not equipped to monitor atmospheric conditions or provide warnings for cyclones. They are not relevant to cyclone early warning systems.

3. **Satellites**: Satellites are artificial objects placed in orbit around the Earth. They are equipped with various instruments that allow them to monitor weather patterns, including the formation and movement of cyclones. Satellites can take photographs and gather data over large areas, making them crucial for early warning systems.

4. **Stars**: While stars are important for navigation and astronomy, they do not play any role in monitoring weather or providing warnings for cyclones.

Based on this analysis, the correct answer is **Satellites**. They play a significant role in the early-warning systems for cyclones by providing critical data and images that help meteorologists predict and track cyclone activity.

### Step-by-Step Solution:
1. **Identify the options**: Helicopter, submarine, satellites, stars.
2. **Analyze each option**:
- Helicopter: Not used for cyclone monitoring.
- Submarine: Operates underwater, irrelevant for weather monitoring.
- Satellites: Monitor weather patterns and provide crucial data for cyclones.
- Stars: Not relevant for weather or cyclone warnings.
3. **Determine the correct answer**: Satellites are essential for early warning systems for cyclones.