Exercises that work the core are exercising muscles found in the
a.
arms
b.
chest
c.
abdomen
d.
legs

Core is your abs so it would be c. abdomen

C is the correct answer. The core muscles are found in the abdomen: the abdominal external oblique, multifidus, transverse abdominal and psoas major muscles. Some other muscles also constitute your core, but these four are the main ones.

I'm not ment for this question

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.