The Soviet Red Army formed at least 42 divisions during the

The Soviet Red Army formed at least 42 divisions during the Second World War which had substantial ethnic majorities in their composition.

a) formed at least 42 divisions during the Second World War which had -- Correct here which clearly refers to WW II. however a comma is required before which.
b) was formed at least 42 divisions during the Second World War that had -- The Soviet Red Army was formed at least 42 divisions is missing a of. The correct sentence would be was formed of at least 42 divisions
c) was comprised of at least 42 divisions throughout World War II who has -- in this sentence the use of who is ambiguous, is it reffering to Red Army or the 42 divisions.
d) formed at least 42 divisions during the Second World War which have had -- have had is not required here, simple past would sufice
e) created some 42 divisions for World War II wherein -- wherein substantial ethnic majorities in their composition. makes no sense