He 'kept his master in the dark' for a long time .
A
in closed doors
B
in a place without light
C
in a cool pace
D
in ignorance
Correct Answer: in ignorance
In the dark - - to keep something secret and not tell people about it. অন্যদিকে in ignorance - - a lack of knowledge or information about something. সুতরাং answer হলো in ignorance।