Thanks, @filipniziol 

I realized CRates are arrays. I guess I have to use another function and add one more layer, right?

CREATE TABLE unpivot_valtype AS
SELECT parse_json(
'{
    "Id": 1234567,
  "Result": {
      "BodyType": "NG",
      "ProdType": "Auto",
      "ResultSets": [
        {
        "R1": {
          "AInt": 1,
          "CRates": [
            {
              "RateA": 11,
              "RateB": 12,
              "RateC": 13
            },
            {
              "RateA": 111,
              "RateB": 112,
              "RateC": 113
            }]
          ,
          "EffPrice": 14,
          "EffRate": 15
        },
        "R2": {
          "AInt": 2,
          "CRates": [
            {
              "RateA": 21,
              "RateB": 22,
              "RateC": 23
            },
            {
              "RateA": 221,
              "RateB": 222,
              "RateC": 223
            }]
          ,
          "EffPrice": 24,
          "EffRate": 25
        },
        "R3": {
          "AInt": 3,
          "CRates": [
            {
              "RateA": 31,
              "RateB": 32,
              "RateC": 33
            },
            {
              "RateA": 331,
              "RateB": 332,
              "RateC": 333
            }]
          ,
          "EffPrice": 34,
          "EffRate": 35
        } } ]
    }
}') as rowData