Lambda expression GroupBy multi-condition grouping

raw data:

Group query sql

select  
 [one_level]
 ,[form_name]
from [appoint_form]
	  group by  
	  [one_level]
      ,[form_name]

How many unique form_names under one_level are grouped?

var cateList = result.Data.List
                .GroupBy(x => new {
    
     One_level = x.One_level, Form_name = x.Form_name })
                .Select(x =>x.Key.One_level).GroupBy(x=>x);        
            List<int> ca_count = new List<int>();
            foreach (var item in cateList)
            {
    
    
                ca_count.Add(item.Count());
            }          

Statistic results:
1 under 3,
2 under 2 and
3 under 3