A sequence satisfies an=nn+1an−1a_n = \frac{n}{n+1} a_{n-1}an=n+1nan−1 for n≥1n \geq 1n≥1 with a0=1a_0 = 1a0=1. What is the value of a9a_9a9?
1/101/101/10
1/91/91/9
1/111/111/11
2/92/92/9