If you answered (a) or (b), you can probably manage this type of class in any form. If (c) is your answer, you should take a careful look at the requirements for a particular class you have in mind; is it organized as self-paced or on a weekly schedule? How many on-campus requirements does it have?
On first glance, it may seem that online classes would be ideal, if your schedule is unpredictable. In fact, many people choose online classes for that very reason. If that is true for you, be careful to consider to two important issues: (1) You should be able to plan reasonable blocks of study time on a regular basis. Many online classes follow a weekly schedule. (2) You should be able to come on campus for meetings or tests at designated times. Many online courses require at least one or two on-campus tests, for example.