Final answer:
A subarray is a contiguous block of an array's elements, which is chosen by selecting a start and end index within the array. The correct answer to the student's question is option 1, as a subarray involves consecutive elements from the original array.
Step-by-step explanation:
A subarray refers to a contiguous block of an array's elements. In any given array, a subarray may represent a single element, the entire array, or any sequence of consecutive elements within that array. To create a subarray, you simply choose a starting index and an ending index, and you include all of the elements within that range. For example, if we have an array with elements [3, 1, 4, 1, 5], a subarray may consist of the elements [1, 4, 1], which starts from the second element of the array and ends with the fourth.
Therefore, in response to the question, "What is a subarray?", the correct option is: 1) A subarray is a contiguous block of an array's elements.
The concept of a subarray is widely utilized in various programming tasks, including calculating maximum subarray sums, searching for subarray with a given sum, and many other applications that involve elements.