The correct options are
A The collection of states in the Indian Union.
D The collection of all the factors of number 56.
A set is a well-defined collection of distinct objects/elements.
The collection of states in the Indian Union and the collection of all the factors of number 56 are well-defined collections of distinct elements, whereas the other collections are not well-defined as they are based on individual's choices and may vary from person to person. Therefore, they aren't sets.