For the allotropic forms of iron, the points of arrest are __________________?

(A)  the points where no further change oc-curs (X)
(B)  the points of discontinuity ()
(C)  constant for all metals (X)
(D) the points where there is no further flow of metal (X)

Answers: For the allotropic forms of iron, the points of arrest are the points of discontinuity.