Considering A as a one-dimensional array, which of the following C++…

Concept

In C and C++, array indexing is zero-based: the element at position k (counting from 1) lives at index k - 1. The subscript operator is also commutative, because a[i] is defined as *(a + i); since addition commutes, a[i] equals i[a] for any array a and integer i.

Applying it here

1. The third element is at index 3 - 1 = 2, i.e. A[2].

2. By commutativity of the subscript, A[2] is the same as 2[A], both expanding to *(A + 2).

3. To send a value to standard output you use the insertion operator <<, so cout << 2[A]; prints that element.

Cross-check

Expanding 2[A] as *(A + 2) confirms it dereferences the same address as A[2], and << (not >>) is the output operator, so the statement both targets the right element and actually prints it.