Which of the following statement is/are correct regarding digestive system of cockroach?

(i) Mouth opens into a short tubular pharynx, leading to a narrow tubular passage called oesophagus.

(ii) Gizzard helps in grinding the food particles.

(iii) A ring of 6-8 blind tubules called hepatic or gastric caecae is present at the junction of foregut and midgut, which secrete digestive juice.

(iv) At the junction of midgut and hindgut is present another ring of 100-150 yellow coloured thin filamentous malphigian tubules which help in removal of excretory products from haemolymph.