Feasibility of the project is under study.

Answer: Option B

Feasibility : the state or degree of being easily or conveniently done.
Unsuitability : the quality of being inappropriate, unsuitable, or unfit.
Impracticability : not practicable : incapable of being performed or accomplished by the means employed or at command an impracticable proposal.
Impropriety : failure to observe standards of honesty or modesty; improper behaviour or character.
Cheapness : the quality of being low in price, especially in relation to similar items or services.

Antonym of Feasibility is Impracticability