
The response rate always refers to the whole survey and not to the single question item which has been selected.

If you have a survey where “multiple responses are allowed” and each of your employees can participate more than once, the response rate chart will still show which percentage of the invited employees participated.
In contrast, other charts will show how many responses you received in total. For example, if 20 employees were invited and each participated twice, “60 responses” will be shown in most graphs, but “100%” will be seen in the response rate chart.