Under what condition is it legal to make a left turn at a red light?

Answer: B — From a one-way street to another one-way street

Making a left turn at a red light is permitted under specific conditions in Massachusetts. It is legal to do so when turning from a one-way street onto another one-way street. This is not only a unique allowance but is designed to facilitate traffic flow and improve efficiency at intersections where turning left from a one-way street can be safely executed. This rule typically requires that the driver comes to a complete stop before making the turn and ensures that the turn can be made without interfering with other vehicles or pedestrians. The driver must also ensure that there are no signs indicating that such a turn is prohibited. This practice contrasts with the conditions of other answer choices, where turning left on red may pose safety concerns or is restricted due to traffic regulations where vehicles approach from multiple directions or different street orientations.