Which of the following statement is true about k-NN algorithm?
1. k-NN performs much better if all of the data have the same scale
2. k-NN works well with a small number of input variables (p), but struggles when the number of inputs is very large
3. k-NN makes no assumptions about the functional form of the problem being solved

A. 1 and 2

B. 1 and 3

C. only 1

D. 1,2 and 3

Answer: Option D