Decision Tree from a dataset

First, I’m not sure if the question fits this site, if not please let me know and I’ll move it.

In my current class (AI) we are studying decision trees. One exercise I have is to build up a tree from a simple raw dataset. I am able to extract the first decision node based on the dataset given but not sure how to build the remaining nodes since none of the remaining attributes has definite answer in the dataset given. Any pointers that put me in the right path are highly appreciated!

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I was able to tell that A1 is the first node in my tree since all rows points to y=1 when A1 is 1