please help me with the right option 8

A manager wishes to build a control chart for a process. A total of five (05) samples are collected with seven (07) observations within each sample. The sample means X-bar) are; 15.36,14.61,16.36,20.28, and 15.77 respectively. Also, the corresponding ranges are: 10.79, 8.37, 2.81,8.17, and 3.31 respectively. The lower and upper control limits of the x-bar chart are respectively Select one: O a. None is correct O b. 12.60, 20.36 O c 13.67, 19.29 O d. 16.55, 11.47 O e. 13.27, 19.69 FACTORS FOR R CHARTS Number of Observations in Subgroup, Factor for X Chart, Lower Control Limit, Upper Control Limit, DA Az D3 2 3- 4 5 3.27 2.57 2.28 2.11 DOD 9 10 11 12 13 14 15 16 17 18 19 20 1.88 1.02 0.73 0.58 0.48 0.42 0.37 0.34 0.31 0.29 0.27 0.25 0.24 0.22 0.21 0 0 0 0 0 0.08 0.14 0.18 0.22 0.26 0.28 0.31 0.33 0.35 0.36 0.38 0.39 0.40 0.41 2.00 1.92 1.86 1.82 1.78 1.74 1.72 1.69 1.67 1.65 1.64 0.20 1.62 0.19 0.19 0.18 1.61 1.60 1.59