Help with an application? Discharged or laid off?

I'm filling out an application and need a little help. They are inquiring about my last job and why I left. It was a positive situation, I wasn't fired for misbehavior anything like that. I was originally hired on as a student to fill in for someone going on maternity leave. When that person decided to stay gone, I was allowed to take her place. The problem was that I was a high schooler and only able to work part time. So the company was actually short a worker for half of the day the whole time I worked there. When business picked up, they gave me the news that they couldn't keep me on part time and had to hire someone full time to take my place. I, having just started my second semester in college, was unable to change my schedule and was told that the next day would be my last day. Is this being laid off, discharged, terminated? What term do I use to convey that I was not let go on negative terms? Specifically, the check box says "Have you ever been discharged or asked to resign from employment? Explain" Does this apply to me? Thanks for your help. :)