What defines a 2D array?

A 2D array, also known as a two-dimensional array, is defined as an array of arrays that represents data in a grid or matrix format. This structure allows for the organization of data in rows and columns, making it particularly useful for representing mathematical matrices, game boards, or image pixel data, among other applications.

In a 2D array, each element can be accessed using two indices—one for the row and one for the column. For example, accessing the element at row i and column j would be done using a notation like array[i][j]. This format is essential for many algorithms and applications that require a structured layout of data, such as performing operations on images, simulating games, or solving problems that naturally fit the grid structure.

The other choices do not define a 2D array accurately. A single value describes a 1D array or a scalar, an array containing only strings refers to the data type of the elements rather than the structural concept, and an array that is only usable in loops does not capture the 2D nature or its common applications in data representation. Hence, the understanding of a 2D array as an array of arrays highlighting its grid-like format is