In following type of feature selection method we start with empty feature set

forward feature selection
backword feature selection
both a and b
none of the above

The correct answer is: A. forward feature selection

Forward feature selection is a type of feature selection method that starts with an empty feature set and adds features one at a time until a stopping criterion is met. This is in contrast to backward feature selection, which starts with a full feature set and removes features one at a time until a stopping criterion is met.

Forward feature selection is often used when the number of features is large and the goal is to find a subset of features that is both relevant and informative. This is because forward feature selection is more likely to find a subset of features that is both relevant and informative than backward feature selection.

However, forward feature selection can be computationally expensive, especially when the number of features is large. Additionally, forward feature selection can be sensitive to the order in which the features are added.

Here is a brief explanation of each option:

  • Forward feature selection starts with an empty feature set and adds features one at a time until a stopping criterion is met. This is the most common type of feature selection method.
  • Backward feature selection starts with a full feature set and removes features one at a time until a stopping criterion is met. This is less common than forward feature selection, but it can be more effective in some cases.
  • Both a and b is not a valid option.