Which of the following statements is always true about an infinite series ∑an that is absolutely convergent?
a) The series converges only if every term an is non-negative.
b) The series might diverge after its terms are rearranged.
c) The series converges, and any rearrangement of its terms converges to the same sum.
d) The terms an must approach 0 faster than 1/n2.