How long will the secondary servers attempt to contact the primary server before it considers that zone is dead and stops responding to queries?

You have the SOA presented below in your Zone. Your secondary servers have not been able to contact your primary server to synchronize information. How long will the secondary servers attempt to contact the primary server before it considers that zone is dead and stops responding to queries?

collegae.edu.SOA,cikkye.edu ipad.college.edu. (200302028 3600 3600 604800 3600)

A.
One day

B.
One hour

C.
One week

D.
One month

Explanation:
The numbers represents the following values:
200302028; se = serial number
3600; ref = refresh = 1h
3600; ret = update retry = 1h
604800; ex = expiry = 1w

3600; min = minimum TTL = 1h