int main() {
    char **last_names;
    last_names = (char **) malloc(sizeof(char) * 4);
    last_names[0] = (char *) malloc(sizeof(char) * 20);
    last_names[1] = (char *) malloc(sizeof(char) * 20);
    last_names[2] = (char *) malloc(sizeof(char) * 20);
    last_names[3] = (char *) malloc(sizeof(char) * 20);


    return 0;
}
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.