int main() {
    char **last_names;
    // 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.
    char *array = malloc(sizeof(char*) * 4);
    last_names = array;
    for(int i = 0; i < 4; i++){
        char array2 = malloc(sizeof(char) * 20);
        last_names[i] = array2;
    }
}
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.