Which GGSCI command(s) show all available information on both read and write
checkpoint for an Extract? 
Example: 1 INFO EXTRACT <group name>
Example: 2 INFO EXTRACT <group name>, DETAIL 
Example: 3 INFO EXTRACT <group name>, SHOWCH
A.
Example 2 only 
B.
Example 3 only 
C.
Examples 1 and 3
D.
Examples 1 and 2
Explanation:
Reference :
http://jianmingli.com/wp/?p=1532
B