Answer: The correct option is (4) 
Step-by-step explanation: Given that in a warehouse, there are 40 guitars, 60 bass guitars, and 20 snare drums. An instrument is randomly selected to check the storage conditions.
We are to find the probability that the selected instrument is a snare drum.
Let, S be the sample space for the experiment of selecting an instrument and E be the event that the selected instrument is a snare drum.
Then,
n(S) = 40 + 60 + 20 = 120
and
n(E) = 20.
Therefore, the probability of the event E is given by

Thus, the required probability is 
Option (4) is CORRECT.