The correct answer is: C. Decontaminate : Sterility
Decelerate is the opposite of speed, while contaminate is the opposite of sterilize. In other words, to decelerate is to slow down, while to contaminate is to make something dirty or impure. Similarly, to sterilize is to make something clean or free of germs, while to decontaminate is to make something safe from contamination.
A. Interpolate is the act of estimating a value between two known values. This is not the opposite of interval, which is simply a period of time or space.
B. Enervate is to weaken or deprive of energy. This is not the opposite of vitality, which is the quality of being full of life or energy.
D. Dessicate is to dry out or dehydrate. This is not the opposite of dryness, which is the state of being dry.