Right option is (c) Factors like pH, temperature and low ionic strength
To explain I would say: Osmotic shock, Alkali treatment and ultrasonication are the methods used to extract enzymes from cells. Osmotic shock and alkali treatment is included in extraction by chemical methods as these methods use 1.4% buffered sucrose and NaOH respectively. Ultrasonication utilizes ultrasonic waves fall into physical treatment category. Hence enzymes can be isolated from cell free extracts using factors like pH, temperature and low ionic strength.