Which blow from west to east, following the boundary between hot and cold air?

1. trade winds

2. sea breezes

3. jet stream

4. polar easterlies

3. jet stream

just type it into google, it's in the definition.

Jet stream

Explanation:

Jet streams are strong winds in the earth's atmosphere that usually blow from west to east. Jet streams are found near the altitude of the tropopause (the transitional area between the troposphere and the stratosphere) and they follow the boundaries between hot and cold air. Jet streams are thought to be the major cause of clear air turbulence.