-- It takes 100 calories of heat to make 10 grams of the stuff 20° warmer.
How much of the heat warms each gram ?
-- It takes 10 calories of heat to make each gram of the stuff 20° warmer.
How much of the heat warms that gram each degree ?
-- It takes 1/2 calorie of heat to make each gram of the stuff 1° warmer.
The specific heat of that stuff is
(1/2 calorie) per gram per °C.
That's choice-3 .