A. unsuitability
B. cheapness
C. impropriety
D. impracticability
Feasibility : practicality.
unsuitability : the quality of being inappropriate.
cheapness : the quality of being low in price, especially in relation to similar items or services.
impropriety : failure to observe standards of honesty or modesty.
impracticability : not practicable.
Antonym of Feasibility is impracticability