Which is the correct characterization of |a| for real a?

A |a| ≤ 0; |a| = a if a ≤ 0; |a| = −a if a > 0

B |a| ≥ 0; |a| = a if a ≥ 0; |a| = −a if a < 0

C |a| ≥ 0; |a| = −a if a ≥ 0; |a| = a if a < 0

D |a| = a for all real a

Correct Answer: Option B