If a substance cannot be broken down chemically into a simpler substance what is it

An Element

Explanation:

An element is a substance that cannot be split into smaller substance. It is made up of one kind of atom and can exist either as molecules  (e.g nitogen) or an atom (e.g argon).

an element

Explanation:

Elements are only composed of one type of atom

i'm hoping this is like a multiple answer question. if it is then it would be, the location of the plants and also the height of the plants since one she wants to know where in her garden the chamomile grows best. but also to see which plants grew better in the location she also has to measure the plant itself. (if you can only choose one answer than it would be c).

it is the most commonly accepted one