Stress strain curve of high tensile steel_______________?

Stress strain curve of high tensile steel_______________?

A. has a definite yield point
B. does not show definite yield point but yield point is defined by 0.1% proof stress
C. does not show definite yield point but yield point is defined by 0.2% proof stress
D. does not show definite yield point but yield point is defined by 2% proof stress

In prestressed concrete______________?

In prestressed concrete______________?

A. forces of tension and compression change but lever arm remains unchanged
B. forces of tension and compressions remain unchanged but lever arm changes with the moment
C. both forces of tension and compres-sion as well as lever arm change
D. both forces of tension and compres-sion as well as lever arm remain unchanged