Which statement is not true about motifs and domains? 

Select one: 

a. Motifs only have structural significance. 

b. Different proteins contain different proportions and arrangements of secondary structural elements. 

c. A supersecondary structure (also called motif) is a combination of various secondary structural elements. 

d. The most common motif is Baß in which an a helix connects two parallel strands of a B sheet. 

e. A long polypeptide chain usually folds into globular clusters which are known as domains