Final answer:
Double solid yellow lines in the center of the road mean that passing is not allowed in either direction, to ensure traffic safety and prevent potential accidents.
Step-by-step explanation:
When double solid yellow lines mark the center of the road and separate oncoming traffic, the correct answer is that passing is not allowed in either direction. The purpose of these lines is to increase traffic safety by clearly indicating that no vehicle should cross them to overtake another vehicle due to potential oncoming traffic and limited visibility of the road ahead. The only exceptions to this rule might be when directed by a traffic officer or in case of emergencies where passing is the only option, but these are very specific scenarios that do not pertain to the general rule.