Phosphine is
I. colourless gas
Il. rotten fish smell
III. highly poisonous
     The correct option is

Phosphine is a colorless, flammable, and explosive gas at ambient temperature that has the odor of garlic or decaying fish. Small amounts occur naturally from the break down of organic matter. It is slightly soluble in water. Phosphine is used in semiconductor and plastics industries, in the production of a flame retardant, and as a pesticide in stored grain.