The table shows the number of candidates recruited by four companies A, B, C and D over the years. Find the ratio of number of candidates recruited by company B in 2019 to the number of candidates recruited by company D in 2020.
| Years | A | B | C | D |
| 2018 | 55 | 40 | 25 | 15 |
| 2019 | 60 | 75 | 50 | 25 |
| 2020 | 65 | 30 | 40 | 65 |
| 2021 | 45 | 35 | 70 | 35 |
1
15 ∶ 11
2
15 ∶ 13
3
13 ∶ 12
4
12 ∶ 11