How To Link Droplist Options With Graphs

I am working on a project that people can use for documenting their actions at work.

I would like to know how after you produce a dropdown list of options, when a person selects a choice, it will add a numerical value of '1' on a graph.

For example:

What is your favourite colour?

droplist options (red, green, blue)

[person selects red]

-> on a graph next to it, the bar for red increases by 1, while green and blue remains at 0.

The droplist will automatically reset after every selection, awaiting retabulation.

PS. Ideally, I would have a button next to it saying "add", so after the option is chosen, the person would click on the button to add the increase on the graph.