What is the role of radula in molluscs?

Closed circulatory system is found in..........

Secondarily asymmetrical type of symmetry is present in

In $Mollusca$,the $osphradium$ has the function of

The body of molluscs is:

Open type of blood vascular system,presence of auricle and ventricle,and presence of haemocyanin respiratory pigment are the characters of