A network engineer configures the following commands on a Cisco router. What does the number $"100"$ represent?

R$2($config$)$#router ospf $108$

R$2($config$-$router$)$#router$-$id $10\mathrm{.}0\mathrm{.}0\mathrm{.}2$

O OSPF hello timer on R$2$

O OSPF area ID on R$2$

O OSPF process ID on R$2$