Answer:
Changes that cannot be reversed are called irreversible changes
Example: if you cook an egg or if something goes bad. these changes can not be reversed.
Canola oil, potato chips, cookies, other sugary treats, bacon, other processed meats, alcohol, milk, other conventional dairy products, refined grain products.
There are more but here are a few, hope this helps!
the answer is the first one: by producing random changes in an organism's genetic code