The following statements are related to plant tissue culture

A. Friable callus provides the inoculum to form cell-suspension cultures.

B. The process known as ‘habituation’ refers to the property of callus loosing the requirement of auxin and/or cytokinin during long term culture.

C. Cellulase and pectinase enzymes are usually used for generating protoplast cultures.

D. During somatic embryo development, torpedo stage embryo is formed before heart stage embryo.

Which one of the following combinations of above statements is correct?