Which city has the highest percentage of sales, and in which year?

Percentage of sales in City-3 in 2016 $$=\frac{5.2}{4.3+3.6+5.2+4.5}\times100=\frac{5.2}{17.6}\times100=29.5\%$$

Percentage of sales in City-1 in 2019$$=\frac{4.1}{4.1+4.3+4.9+4.9}\times100=\frac{4.1}{18.2}\times100=22.5\%$$

Percentage of sales in City-4 in 2017$$=\frac{4.6}{3.5+3.9+4.3+4.6}\times100=\frac{4.6}{16.3}\times100=28.2\%$$

Percentage of sales in City-2 in 2018$$=\frac{4.2}{3.9+4.2+4.9+5.1}\times100=\frac{4.2}{18.1}\times100=23.2\%$$

$$\therefore\ $$The percentage sales in City-3 in 2016 is highest

Hence, the correct answer is Option A