int main() {
    char **last_names;

    **last_names = malloc(sizeof(char*) * 4);
    last_names[0] = malloc(sizeof(char) * 20);
    last_names[1] = malloc(sizeof(char) * 20);
    last_names[2] = malloc(sizeof(char) * 20);
    last_names[3] = malloc(sizeof(char) * 20);
    // Assign a dynamically allocated char * array of length 4 to last_names. 
    // Then, allocate a character array of length 20 for each element of the array 
    // pointed to by last_names.