I've been struggling with "distributional grammar", in particular with two SC cases:

Unlike other arachnids, which have their nerve cells evenly distributed along their bodies, the scorpion's nerve cells are clustered in its head, like a mammal's.

A bodies, the scorpion's nerve cells are clustered in its head, like a mammal's

B bodies, the scorpion's head had a cluster of nerve cells, as a mammal does

C body, the scorpion has a cluster of nerve cells in its head, as a mammal does

D body, nerve cells are clustered in the scorpion's head, like a mammal's

E body, a cluster of nerve cells is in the scorpion's head, like a mammal's


I cannot figure out why it is "their body", while in another example it is used in this way:

Mr.Kryzak recommended that Social Security laws be changed so that medical plans be extended to those women who lose health coverage when her husband dies.

(A) be extended to those women who lose health coverage when her husband dies
(B) be extended to those women who losing health coverage when their husband dies
(C) are extended to those women who lose health coverage when their husband dies
(D) are extended to those women who lose health coverage when their husbands die
(E) will be extended to those women losing health coverage when her husband dies

In that case, "their husbands" is used, instead of "their husband". Is there a rule for that?