The direction in which the Earth and the other solid planets-Mercury,Venus, and Mars-Spins were determined from collisions with giant celestial bodies in the early history of the solar system

a) Spins were determined from
b) Spins were Determined because of
c) Spin was determined through
d) Spin was determined by
e) Spin was determined as a result of

Which is the Subject in this question, is it either The direction or the Earth and the other solid planets,

if The direction(Singlular) is Subject then the verb will be Spins(Plural)

If the Earth and the other solid planets (S) is subject then the verb will be Spin(P)

On what basis either was or were are to be eliminated and choose the right one.

Kindly Explain !

OA : D

DJ