The manual gives one specific speed range you must NOT drive at in fog. What is it?
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A.
Above the posted speed limit.
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B.
Faster than the surrounding traffic.
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C.
Between 5 and 10 mph. Correct
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D.
Under 30 mph in dense fog.
The answer is "Between 5 and 10 mph."
The manual names 5-10 mph as the range to avoid in fog, because a vehicle crawling at that speed gets rear-ended by drivers who cannot see it until it is too late. Choice D reads as extra caution, and drivers taught that slower is always safer in poor visibility land there instead of on the specific number the manual sets.
The traps in the wrong answers
A. Above the posted speed limit.
Speeding in fog is dangerous, but it is not the specific range this sentence in the manual names. This answer pulls the general 'do not speed in bad weather' idea and treats it as the answer to a specific figure.
B. Faster than the surrounding traffic.
The manual tells you to slow down in fog, not to match the fastest driver on the road. This answer applies the flow-of-traffic guidance from clear-weather driving to a fog situation the manual treats differently.
D. Under 30 mph in dense fog.
The manual sets no 30 mph ceiling for fog. This answer substitutes a cautious-sounding cap for the 5-10 mph range the manual actually names.
This question tests your knowledge of Adverse Conditions in Illinois. Source: Illinois Rules of the Road, "Weather Conditions: Fog," p.84..
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