Statement-1: For $\mathrm{n} = 3, \mathrm{l}$ may be 0, 1 and 2 and m may be 0, ± 1 and ± 2. 

Statement-2: For each value of n, there are O to (n -1) possible values of l, for each value of l, there are 0 to ± l values of m.

Reason is the proper justification for Assertion, and both Assertion and Reason are true.
The first claim is now: For n=3, l may be 0 through ±1, and m may be 0 through ±2, respectively.
For any number of n, there are 0 to (n -1) possible l values, and for each l value, there are 0 to ±l possible m values.