At an intersection with its own separate signal head for the left-turn lane, your green left arrow has ended and gone red, while the through traffic beside you now has a green light. A gap opens in oncoming traffic. May you turn left?

Correct answer: C. No — with a separate left-turn signal, you may not start a left turn once the through traffic's green appears

No. At a fully protected left turn the left-turn lane has its own lights running their own sequence — green arrow, then yellow, then red — while straight-through and right-turning traffic gets a green of its own. The Handbook is explicit: "In these intersections, you may not begin turning left after the green light appears for traffic going straight ahead or turning right." Your red arrow still means red, however inviting the gap looks. The only concession is for a turn already under way: "If the light turns yellow while you are in the intersection, complete your turn with caution." Compare this with an ordinary green ball, where you may turn left once the way is clear — the whole point of a protected left is that the permission is not open-ended.

Source: MTO Driver's Handbook: Traffic lights — Fully protected left turn