What best describes nested loops?

Nested loops refer to the concept of placing one loop inside another loop. This means that for each iteration of the outer loop, the inner loop will execute completely. This structure is particularly useful when dealing with multi-dimensional data, such as arrays or matrices, where you need to handle operations on rows and columns simultaneously.

For instance, in a nested loop scenario, the outer loop might iterate through each row of a matrix, while the inner loop processes each element within that row. This allows for complex data manipulation and makes it easier to perform operations that require two levels of iteration.

The other options do not accurately capture the essence of nested loops. A single loop executing multiple times implies repetition but does not involve the concept of one loop contained within another. A loop having no internal structure doesn't represent the relationship between loops that nested loops illustrate. Lastly, a sequential arrangement of loops suggests that loops are running one after the other rather than demonstrating how one loop is contained within another. This fundamental understanding enhances a developer's ability to handle complex data structures effectively.