The following bar graph shows the production of pens (in lakhs) by three companies M, N, O from 2018 to 2022. What is the ratio of the average production of Company O in the period 2019-2021 to the average production of Company M in the same period?
1
55 ∶ 46
2
66 ∶ 79
3
64 : 73
4
64 ∶ 65