Imagine a machine learning task where the instances are customers. You know the phone number for each customer and their occupation $($one of seven categories$).$ You're wondering how to turn these into features.

Which is false?

a$.$For some models, you may want to turn the occupation into several numeric features.

b$.$Whether to use the occupation directly or turn it into a numeric feature depends on the model.

c$.$You can extract several useful categoric features from the phone number.

d$.$The phone number is an integer, so you should use it as a numeric feature.