Which key principle of developmental systems theory underlies the observation that certain experiences bias children from birth to be predominantly left- or right-handed, but the process of development of hand preference can be delayed or even reversed (e. g., from left to right or right to left) within the first 5 years of postnatal development?

Well if you pick a machine to work on and that's gonna be your exercise if you don't stick to that machine your muscle strength your muscle mass rather will change because you haven't been doing it you change something in your exercise routine which changes your body's form of dealing with things for example you might become weaker or stronger depending on what kind of exercises you do in whether or not the machine you picked actually your muscles grow.

Exactly what he said he smart

The answer is either 3 or 4