I wrote the following app to examine the array's constructors:

using System;
using System.Reflection;

namespace NewArray
{
 class Program
 {
   static void Main(string[] args)
   {
     Type IntType = typeof(int);
     Type IntArrayType = IntType.MakeArrayType(5);
     ConstructorInfo[] Constructors = IntArrayType.GetConstructors();
     foreach (ConstructorInfo Constructor in Constructors)
     {
       ParameterInfo[] Parameters = Constructor.GetParameters();
       string[] Types = new string[Parameters.Length];
       for (int Index = 0; Index < Parameters.Length; Index++)
         Types[Index] = Parameters[Index].ParameterType.Name;
       Console.WriteLine("({0})", String.Join(", ", Types));
     }
     Console.ReadLine();
   }
 }
}

//

It gives the following output:

(Int32, Int32, Int32, Int32, Int32)
(Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32)

//

That is, you can pass either five lengths (one for each dimension) or
five pairs of start/stop indices. Thus,

 int[, , , ,] A = (int[, , , ,])
   Activator.CreateInstance(IntArrayType, 3, 3, 3, 3, 3);

is exactly analagous to (but slower than)

 int[, , , ,] B = new int[3, 3, 3, 3, 3];