Final answer:
Given the array declaration, int a[20];The last (legal) element is written as:a[19].
The answer is option ⇒d) a[19]
Step-by-step explanation:
The correct answer for the last (legal) element of the array int a[20]; is a[19].
In C and C++ arrays are zero-based, which means that the first element is at index 0 and the last element is at index n-1, where n is the size of the array.
In the given declaration, int a[20];, we have an array named 'a' with a size of 20. Since the indexing starts from 0, the last element of the array will be at index 19.
The answer is option ⇒d) a[19]