When performing regression or classification, which of the following is the correct way to preprocess the data?

A) Normalize the data -> PCA -> training

B) PCA -> normalize PCA output -> training

C) Normalize the data -> PCA -> normalize PCA output -> training

D) All of the above

Correct Answer : Normalize the data -> PCA -> training

Explanation : You need to always normalize the data first. If not, PCA or other techniques that are used to reduce dimensions will give different results.