Answer:
100% - 75.3% = 24.7%
c is correct
Explanation:
If the probability of getting a particular result in an experiment is 75.3%. 
As we know, the probability of occurring and not occurring is 100% 
P( getting result ) = 75.3%
Let probability of not getting result be x 
So, P( not getting result ) = x 
P(getting result) + P(not getting result) = 100%
 75.3% + x = 100%
 x = 100% - 75.3%
 x = 24.7%
Hence, The probability of not getting result is 27.4%