Which of these fits gap (iv)?

Directions: Read the following passage having some numbered gaps.

Man used sticks and stones long before he dared to interfere with fire, ____(i)_____ the early man like all wild creatures dreaded the fire. Fire, of course existed; for lightning must ____(ii)____ have set the forests ablaze just as it does today and in those days, today’s volcanoes were ___(iii)___ they now are. The forgotten hero who first dared to tame fire for his own use, was the greatest of early inventers; for once man had fire, ____(iv)____.