A. someone opened the window because he or she was too warm. b. someone opened the window because they be too warm. c. someone opened the window because them was too warm. d. someone opened the window because they were too warm.

d

explanation:

the unique function that the video specifically ascribes to sins near tunnels is "prohibiting certain cargo". tunnels have specific control signs such as minimum and maximum speed, the appropriate use of headlight and prohibited cargo. for your own safety it is important you understand the signs when approaching a tunnel.