score:3

Accepted answer
select t).Count() 

or going for terse-ness in the other direction:

"".GetType().Assembly.GetTypes().Count(t => t.IsPublic && t.IsEnum)

score:0

Off the top of my head, you would need to group by t

         from t in "".GetType().Assembly.GetTypes()
         where t.IsEnum && t.IsPublic
         group t by t into x
            select x.Count()

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