What describes a collection of nodes (or vertices) and edges that connect pairs of nodes?

A graph is defined as a collection of nodes (or vertices) and edges that connect pairs of nodes. In graph theory, this structure represents relationships or connections between different entities. Each node can represent an individual entity, while each edge represents a connection or relationship between those entities. Graphs can be directed, where the connections have a specific direction, or undirected, where the connections are bidirectional.

This concept is fundamental in many areas such as computer science, social network analysis, and logistics. Graphs can be used to model various systems such as computer networks, where nodes represent computers and edges represent communication links, or social networks, where nodes represent individuals and edges represent relationships between them.

The other options listed, such as queues, arrays, and stacks, refer to different data structures used for managing collections of data but do not involve relationships between nodes in the way graphs do. Queues and stacks represent ordered collections of elements with specific rules for adding and removing elements, while arrays are contiguous blocks of memory that store items of the same type in a defined order. These structures serve different purposes and do not inherently capture the connectivity or relationships among elements like a graph does.