Confusion about what state to file 1099-MISC "other income" when 3 states are involved?

My daughter goes to college in Pennsylvania.  She received $4,000 in funding from her college for her summer internship in California.  We live in Massachusetts.  What state should she declare the $4,000 reported on the 1099-MISC "Box 3-Other Income", PA, CA or MA?  Thanks so much for your help!