Use the universal set U = {a,b,c,. y, z} and the characteristic function for the specified subset to compute the following function value:78] NOTE:

Use the universal set U= {a,b,c,..... y, z} and  the characteristic function for the specified subset to compute the following function value:

[2.78]   NOTE: Please ignore the "bracket" as it is the closest I could find to notation for a ceiling function. This could be simpler then I am making it and I think all I have to do is utilize the ceiling function. c(2.78)=3 but the first part of the question throws me off. 

a. 3

b. -3

c. -18

d. 14