(ASP.NET) สอบถาม jQuery Ajax Post by Json Data แล้วทางฝั่ง codebehind จะรับ object ได้อย่างไรครับ

var data = [{ "User": "test1", "Password": "pwd1" },
 { "User": "test2", "Password": "pwd2" }];

$.ajax({
url:"test.aspx/RequestData",
type:"POST",
contentType: "application/json; charset=utf-8",
data: JSON.stringify(arr),
dataType: "json",
success: function (msg) {
     $('#lbClick').text(msg.d); //.split(';');
}
});

[System.Web.Services.WebMethod]
public statis string RequestData(XXXXXX)
{

}