Hello student, all these 3 courses are not seperate. There are connected with each other. First, you can learn basics with data science and then using those, you can code and alogrithms can be made using machine learning. With these, you can build models and further advanced core concepts can be learnt in artificial intelligence. So three of them have equal scope. Choose the one which you are more intrested in. Data science is the concepts an easier. ML and AI is the core and advanced. Each of them is demanding and developing these days and everything has a very good scope. So chose one whichever you are intrested in.