Question

the pronoun it has an unclear antecedent. How should the sentence be rewritten to clearly and correctly communicate the intended meaning?
A.A torso mannequin is sometimes used as an alternative to a full-sized one because they are cheaper and smaller.
B.A torso mannequin, which is cheaper and smaller, is sometimes used as an alternative to a full-sized one.
C.A torso mannequin is sometimes used as an alternative to a full-sized one, which is cheaper and smaller.