In order to get fit if youre under weight you do need to put on weight. But that does not means that you put on some extra fat by eating junk.
In order to get a healthy body and a toned one with exercise you need to take a few supplements as well as keep a proper protein and carbs diet so that you can build some muscle mass and get in shape.
The reason why you should incluce something like a weight routine in your life and especially as a part of your exercise routine is mostly to increase your muscle mass I.
But the truth is that your bone density also increases and your flexibility can also increase to a smaller amount.
So the most true answer here would be I, II, and III. But most likely I would be what is required of you to answer.
