High carbon content in the steel causes A. Decrease in tensile strength but increase in ductility B. Increase in tensile strength but decrease in ductility C. Decrease in both tensile strength and ductility D. Increase in both tensile strength and ductility

The correct answer is: B. Increase in tensile strength but decrease in ductility

Tensile strength is the maximum amount of tensile stress that a material can withstand before it breaks. Ductility is the ability of a material to be stretched or deformed without breaking.

High carbon content in steel increases the tensile strength of the steel. This is because the carbon atoms in the steel form a solid solution with the iron atoms, which makes the steel harder and stronger. However, high carbon content also decreases the ductility of the steel. This is because the carbon atoms make it more difficult for the iron atoms to slide past each other, which makes the steel more brittle.

Therefore, the correct answer is B.