In a fabric manufacturing factory, the quality control process using control charts from SPC. In an hour there are a total of 5 samples are taken each having 4 observations regarding the thickness of fabric in measured in millimeters. In a particular hour, the sample means (X-bar) are noted to be: 172.11, 219.58,208.24. 112.44 and 123.30 respectively. In the same sample, the corresponding ranges are: 13.17.13.38. 15.34, 13.04 and 13.02 respectively What are the lower and upper controllimits for the R chart? O a 0,31.47 O b. 0,30.99 Oc. 0,31.17 od 0,28.17 e. None is correct of 0,29.17