The answers are 1, 3, and 5.
A symbol or set of characters in a programming statement whose value can be changed
Crowdsourcing is used by mobile application that allows users to report the location of a pet that appears to be lost.
<h3>What is a mobile application?</h3>
A mobile application is known to be a kind of computer app or program that has been made to handle or run itself on a mobile device e.g. phone, etc.
Conclusively, the option that best describes a system that uses crowdsourcing is the mobile application that allows users to report the location of a pet that appears to be lost and upload a photo that is made available to other users of the application and thus everyone can help to look for it.
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