What is the source of the allusion in the sentence below?
Jacob dropped out of college to travel the world, but a year later, the prodigal son returned home and re-enrolled.

 - British history
 - the Bible
The source of the allusion prodigal son is the Bible.
In a Biblical parable, the prodigal son irresponsibly spends the inheritance given to him by his father. When he returns home, he expects to be shamed, but his father forgives him.
The allusion prodigal son means a person who behaves recklessly but later makes a repentant return.