If ∑n=1∞an\sum_{n=1}^{\infty} a_n∑n=1∞an is a series of positive terms and limn→∞an+1an=1\lim_{n \to \infty} \frac{a_{n+1}}{a_n} = 1limn→∞anan+1=1, what can you conclude?
The series converges absolutely
The test is inconclusive
The series converges
The series diverges