To visualize counts of gender by birth year, with each gender having its own color, the appropriate line of code from the provided options would be:
catplot(x = 'birthYear', col = "gender", data = data, hue = 'gender', kind = "count")
This code specifies that the x-axis should represent 'birthYear', and it uses the hue
parameter to differentiate counts based on 'gender', allowing for distinct colors for each gender.