Final answer:
Time is not a highway condition that requires adjusting speed; the correct conditions are visibility, traction, and space.
Step-by-step explanation:
The three major highway conditions that require drivers to adjust their speed are visibility, traction, and space. Therefore, time is not one of the conditions that directly require you to adjust your speed when driving on the highway.
Visibility refers to how well you can see the road and traffic, traction is the grip your tires have on the road, and space refers to the distance around your vehicle that you need to maintain for safety. Adjusting your speed based on these conditions is crucial for safe driving.