Map and flatMap

You have a list numbers:

List<Integer> numbers = Stream.of(1, 2, 3, 4, 5).collect(Collectors.toList());

What numbers does the list generated contain?

a)

List<Integer> generated = numbers.stream()
        .flatMap(n -> Stream.generate(() -> n).limit(n))
        .collect(Collectors.toList());

b)

List<Integer> generated = numbers.stream()
        .flatMapToInt(n -> IntStream.rangeClosed(1, n))
        .boxed()
        .collect(Collectors.toList());

c)

List<Integer> generated = numbers.stream()
        .flatMapToInt(n -> IntStream.iterate(n, val -> val + 1).limit(n))
        .boxed()
        .collect(Collectors.toList());

d)

List<Integer> generated = numbers.stream()
        .flatMap(Stream::of)
        .collect(Collectors.toList());