Which of the Following Statement Is/are True of Rate Law

Multiple Choice

Which of the following statement is/are true of rate law?
1) The proportionality constant k, called the rate constant, and n, called the order of the reactant in the rate law, must be determined by experiment.
2) The concentrations of the products of a chemical reaction do not appear in the rate law.
3) The order of a reactant in the rate law can only be a positive integer.

A) 1 only​
B) 2 only​
C) 3 only​
D) 1 and 2​
E) 2 and 3​