Law and transgression in Galatians 3:19 and 3:24

The law was "added because of (or for) transgression" and "was put in charge to lead us" could mean one of the following:

1. It managed and restrained our sin. 
2. It exposed sin and declared it to be violation of God's law.
3. It provoked and deepened by making God's demands explicit.
4. It awakened guilt and so gave individuals a sense of their need for forgiveness.

I think number 2 suits the flow of God's argument best, although I think all four are true and taught elsewhere in Scripture.