Answer
Александр
The correct choice:
2018.
Green marks that are used in calculations.
We need to summarize the number of applications from different companies for each year.
2017. 50 + 110 + 70 = 230 apps.
2018. 150 + 130 + 170 = 450 apps.
2019. 100 + 210 + 50 = 360 apps.
2020. 50 + 110 + 180 = 340 apps.
The most applications were developed in 2018.
Answer: 2018.