Elastic nut is a locking device in which__________________?

A. one small nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
B. a slot is cut partly in middle of nut and then slot reduced by tightening a screw
C. hard fiber or nylon cotter is recessed in the nut and becomes threaded as the nut is stewed on the bolt causing a tight grip
D. through slots are made at top and a cotter-pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at other end
E. none of the above

Slenderness ratio of a long column, is_________________?

A. Area of cross-section divided by radius of gyration
B. Area of cross-section divided by least radius of gyration
C. Radius of gyration divided by area of cross-section
D. Length of column divided by least radius of gyration

Ignition lag is__________________?

A. the time taken by fuel after injection (before top dead center) to reach upto auto-ignition temperature
B. time before actual fuel injection and the pump plunger starts to pump fuel
C. time corresponding to actual injection and top dead center
D. time corresopnding to actual ingition and top dead center
E. none of the above