What Is the Difference Between Atactic Polymer and Isotactic Polymer

What is the difference between atactic polymer and isotactic polymer?

A) Atactic polymer has an irregular structure while in isotactic polymer identical functional groups have the same orientation on the polymer chain.
B) Atactic polymer has a regular zig-zag structure while in isotactic polymer identical functional groups have the same orientation on the polymer chain.
C) Atactic polymer has the same functional groups on one side of the polymer structure while in isotactic polymer has random distribution of functional groups in its structure.
D) Atactic polymer has an irregular structure while in isotactic polymer identical functional alternate back and forth along the polymer chain.
E) Atactic polymer has identical functional groups alternating back and forth along the polymer chain while in isotactic polymer identical functional groups have the same orientation on the polymer chain.