%_The efficiency of a screw jack is maximum, when (where ≈í¬± = Helix angle, and ≈ì√ú = Angle of friction.)_%

≈í¬± = 90¬¨‚àû + ≈ì√ú

≈í¬± = 45¬¨‚àû + ≈ì√ú/2

≈í¬± = 45¬¨‚àû - ≈ì√ú/2

≈í¬± = 90¬¨‚àû - ≈ì√ú

%_The efficiency of a screw jack is maximum, when (where ≈í¬± = H

1.	%_The efficiency of a screw jack is maximum, when (where ≈í¬± = Helix angle, and ≈ì√ú = Angle of friction.)_%
A.	≈í¬± = 45¬¨‚àû + ≈ì√ú/2
B.	≈í¬± = 45¬¨‚àû - ≈ì√ú/2
C.	≈í¬± = 90¬¨‚àû + ≈ì√ú
D.	≈í¬± = 90¬¨‚àû - ≈ì√ú
Answer» C. ≈í¬± = 90¬¨‚àû + ≈ì√ú