What is the default periodic interval at which RIPv1 sends routing updates?

A.
15 seconds

B.
30 seconds

C.
45 seconds

D.
60 seconds

E.
90 seconds

F.
RIPv1 only sends routing updates when the topology changes.

Explanation:
“Originally, each RIP router transmitted full updates every 30 seconds.”
http://en.wikipedia.org/wiki/Routing_Information_Protocol