Plz answer me of question 18 and 19

Dear student,
Please find below the answer:

18. Option (b) is correct i.e. Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
Mitochondria are strange organelles because they contain their own genetic material and can behave like an individual cell. They produce energy in the form of ATP molecules.

19. Option (d) is correct.
Peptic ulcers are caused by a bacterium known as Helicobacter pylori. It can be treated by killing or eliminating these bacteria from the stomach through medications.

Hope this clears your doubt.
Regards.