Final answer:
An exact percentage increase in stopping time for a truck or bus in adverse weather conditions cannot be determined without specific context or data. Safety guidelines generally advise doubling the following distance in such conditions, which would be a 100% increase, but the provided choices do not list this option.
Step-by-step explanation:
The question doesn't provide sufficient context to ascertain the exact percentage increase in stopping time for a truck or bus in adverse weather conditions. However, it's common knowledge that stopping distances can increase significantly due to factors such as rain, snow, or ice, which reduce tire traction.
To address questions related to typical stopping distances, one would need specific information about road conditions, vehicle conditions, and the nature of the weather impacting the stopping distance. Generally, it is advised for drivers to increase following distance by 100%, effectively doubling the stopping distance in adverse conditions, although this is not an option listed in the provided choices.
Without specific context or data, it's not possible to provide an exact answer to the percentage increase in stopping time for heavy vehicles. When in actual driving scenarios, it's best to follow safety guidelines and increase following distances as much as practically possible to account for longer stopping times.