Have survey email invitations been opened?

Hi All, We recently launched our first transactional survey triggered by Salesforce data. The survey has been live for a few weeks now, and 20+ invitation emails have been triggered as well as a handful of reminder emails. No surveys have been completed yet, which is surprising given that we're offering a $20 Tango Card incentive for a very short survey. All diagnostics in Qualtrics and Salesforce indicate that the emails were successfully sent, and only one bounced. Question - Is Qualtrics capable of determining if survey email invitations have been opened by the recipient? If yes, how do I access this diagnostic? Thanks in advance for your help! Mike