You can select any number of submissions and send response emails to those submissions.
Here's how to send an email as a response:
Select the submissions to which you want to respond.
Click on the Take Action drop-down button in the subheader.
Click on the Send email option from the drop-down to open a form in a pane.
Select a predefined email template or compose an email from the pane.
Click on Send to send the response mail to all submissions with a valid email address.