Clear and correct
- Geology is the study of the (nonliving) Earth (living things go in zoology, life science, etc.).
Sentences like this are not simple English because the form is made ridiculously complex and inaccurate by the bracketted material. Small words alone do not make "simple English". What, one my ask, is the word "Earth" doing isolated between two sets of brackets? Why are there two fullstops? What on earth is meant by "living things go into zoology?
Bracketted material in a sentence almost always makes the sentence less easy to understand. If you are stating a fact, make another sentence of it. If you are interpreting a hard word, put it in brackets.