Final answer:
The correct answer is c. both lanes, unless a sign prevents it. Drivers can turn left from either lane in a situation where a left turn lane can be made from two designated left-turn lanes.
Step-by-step explanation:
In the given options, the correct answer is c. both lanes, unless a sign prevents it. If a left turn lane can be made from two designated left-turn lanes, it means that drivers can turn left from either lane. However, they should still follow road signs and signals to ensure safe and legal turning movements.