When making a left turn where there are two available turn lanes, a driver should begin the turn in the rightmost lane because:

If making a left turn where there is more than one available turn lane, you should always choose to begin your turn in the rightmost lane. Large vehicles often have to swing right to make left turns. Because of this, it is safer for you to have other left-turning traffic to your left instead of to your right. This will allow you to have the best possible view of other turning vehicles and will lower the risk of your vehicle colliding with them.