The given data shows the number of mobiles (in thousands) manufactured by companies C-1, C-2, C-3 and C-4 in 2017, 2018 and 2019.

Which company manufactured the least number of mobiles across all the years?

From the graph,

Number of mobiles (in thousands) manufactured by company C-1 in 2017, 2018, 2019 = 59 + 65 + 68 = 192

Number of mobiles (in thousands) manufactured by company C-2 in 2017, 2018, 2019 = 62 + 67 + 72 = 201

Number of mobiles (in thousands) manufactured by company C-3 in 2017, 2018, 2019 = 68 + 71 + 74 = 213

Number of mobiles (in thousands) manufactured by company C-4 in 2017, 2018, 2019 = 59 + 62 + 65 = 186

$$\therefore\ $$The company C-4 manufactured the least number of mobiles across all the years

Hence, the correct answer is Option C