There are various kinds of courses in PHD. For which course you are eligible, what course you can take is dependent on your previous education. Here are few phd programs,

• PHD in bioscience
• PHD in applied science
• PHD in human science
• PHD in economics
• PHD in geography etc.,

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Even Job opportunities depends on which course you have done. So let us know about the course you have done or the course you want to do.