What Is the Difference Between an Organic Structure and a Mechanistic

What is the difference between an organic structure and a mechanistic structure?

A) an organic structure is not bound by job descriptions while in mechanistic they are
B) an organic structure has longer communication channels while in mechanistic the communication channel is short
C) an organic structure has large spans of control while in mechanistic the span of control is small
D) an organic structure has very close supervision while in mechanistic supervision is random