(10) Which statement is incorrect regarding polymers/elastomers?
(A) Thermosets are highly cross-linked polymer chains that form a three-dimensional network structure.
(B) In thermosets, cross linking is not reversible； once formed, the thermosets cannot be refused or conveniently recycled.
(C) Vulcanization is a process which uses nitrogen atoms to link polymer chains in rubber.
(D)Thermoplastics such as polyethylene has a flexible linear chain structure (straight or branched)