If limit n->∞ Σ (from n=1 to n) of "a sub k" exists and has a finite value, the infinite series Σ (from n=1 to n) of "a sub k"

a) unbounded
b) convergent
c) increasing -----> my answer. Can you check for me, pls? Thanks
d) divergent

nope. the terms might be negative.

But if the infinite sum exists and is finite, the partial sums converge to that value.

and if the terms are a sub k, then the sum is Σ (from k=1 to n)