Trough and ridge are

Trough and ridge are

1. elongated area of low pressure and of high pressure respectively.
2. elongated areas of low pressure.
3. elongated areas of high pressure.
4. elongated area of high pressure and of low pressure respectively.

• Answer: The correct option is A
• Explanation:

  A trough is an elongated area of relatively low atmospheric pressure.

  A ridge is an elongated area of relatively high atmospheric pressure.