Which of the following has highest specific strength of all structural materials?

Answer: Option B

Titanium alloys is used to control grain size growth, which improves toughness. Also transforms sulfide inclusions form elongated to globular, improving strength and corrosion resistance as well as toughness and ductility.
Titanium alloys is a very strong, very lightweight metal that can be used alone or alloyed with steels. It is added to steel to give them high strength at high temperatures. Modern jet engines used titanium steels.