On a weather map, which type of front is shown by a line with semi-circles extending from one side?

Explanation:

A warm front is indicated on the line by red semi-circles pointing away from the warmer air and pointing in the direction towards which the warm air is moving. Along sections of the polar front, cold and warm air masses may move differentially with for one another.

the answers for the whole quick check is

1. b

2. b

3. a

4. c

5. b

6. a

7. d