The following table shows the production of cars in a company from 2016 to 2020.

Years	2016	2017	2018	2019	2020
A	30	23	39	25	18
B	16	10	14	12	8
C	15	18	19	25	30
D	31	12	21	19	20

There was a continuous increase in the production of cars of which type during the period 2016 to 2020?

The correct answer is C.

To determine which type of car showed a continuous increase in production during the period from 2016 to 2020, let us examine the production data for each car type year by year from the table:

Car Type A:
2016: 30
2017: 23 (Decreased from 30)
Since production dropped in 2017, car type A did not have a continuous increase.

Car Type B:
2016: 16
2017: 10 (Decreased from 16)
Since production dropped in 2017, car type B did not have a continuous increase.

Car Type C:
2016: 15
2017: 18 (Increased from 15)
2018: 19 (Increased from 18)
2019: 25 (Increased from 19)
2020: 30 (Increased from 25)
As seen from the numbers, production increased every single year from 2016 to 2020:

$15<18<19<25<30$

Car Type D:
2016: 31
2017: 12 (Decreased from 31)
Since production dropped in 2017, car type D did not have a continuous increase.

Therefore, car type C is the only car type that experienced a continuous increase in production throughout the period 2016 to 2020.