PROGRAM CODE:

//Header section
#include <iostream>

using namespace std;

int main() 
{
    // Declare the 2D array 'a' with dimensions 4 rows and 5 columns.
    int a[4][5];

    // Nested loops to iterate through each element of the array.
    // Outer loop for rows, and inner loop for columns.
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 5; j++) {
            // Prompt the user to input a number and store it in the array.
            cout << "Enter a number for row " << (i + 1) << ", column " << (j + 1) << ": ";
            cin >> a[i][j];
        }
    }

    // Output the filled array to verify the input.
    cout << "Array 'a' after input:" << endl;
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 5; j++) {
            // Output each element, separated by a space, in the same row.
            cout << a[i][j] << " ";
        }
        // Move to the next row after finishing a row.
        cout << endl;
    }

    return 0;
}

OUTPUT:

Enter a number for row 1, column 1: 10
Enter a number for row 1, column 2: 29
Enter a number for row 1, column 3: 30
Enter a number for row 1, column 4: 40
Enter a number for row 1, column 5: 50
Enter a number for row 2, column 1: 70
Enter a number for row 2, column 2: 99
Enter a number for row 2, column 3: 1
Enter a number for row 2, column 4: 8
Enter a number for row 2, column 5: 9
Enter a number for row 3, column 1: 10
Enter a number for row 3, column 2: 200
Enter a number for row 3, column 3: 50
Enter a number for row 3, column 4: 45
Enter a number for row 3, column 5: 90
Enter a number for row 4, column 1: 88
Enter a number for row 4, column 2: 66
Enter a number for row 4, column 3: 33
Enter a number for row 4, column 4: 22
Enter a number for row 4, column 5: 11

Array 'a' after input:
10 29 30 40 50 
70 99 1 8 9 
10 200 50 45 90 
88 66 33 22 11