Which of the following statements about vector subtraction is correct?
a) Vector subtraction is commutative, i.e. a−b=b−a for all vectors.
b) Vector subtraction always yields a vector whose magnitude equals ∣a∣−∣b∣.
c) The associative relation (a−b)−c=a−(b−c) does not hold in general.
d) Vector subtraction preserves the magnitude of the original vectors.