Which of the following is a two-dimensional bar code that can be scanned and decoded with a smartphone reader app?

A QR code is a type of two-dimensional barcode that can store a significant amount of information, such as URLs, text, and contact details. Its design allows it to be scanned quickly and easily with a smartphone equipped with a camera and a reader application. This capability makes QR codes popular in marketing and information sharing, as users can access content directly by scanning the code. Furthermore, the technology behind QR codes can withstand some damage and distortion while still being readable, which adds to their utility.

Other types of barcodes, such as UPC codes, data matrix codes, and standard barcodes, primarily operate as one-dimensional codes. While they can be useful for tracking inventory and identifying products, they typically require specialized barcode scanners rather than smartphone apps for decoding. Each of these barcodes serves distinct purposes, but the versatility and ease of access that QR codes provide with smartphone technology uniquely qualify them as two-dimensional barcodes suitable for a wide range of applications.