Singers (E)nrique, (K)aty, (R)ihanna, and (B)runo are performing a charity concert for world hunger and their order of appearance will be chosen randomly. The outcomes in the sample space be represented as strings of letters such as ERBK or KERB. Complete parts (a) through (c) below. (a) How many elements are there in this sample space? (Type a whole number.) (b) Express the event "Rihanna and Bruno perform consecutively" as a set. Choose the correct answer below. OA. (RBKE,RBEK,KRBE, ERBK,KERB,EKRB} B. (RBKE,RBEK,KRBE,ERBK,KERB,EKRB,BRKE,BREK,KBRE,EBRK,KEBR,EKBR) OC. (RBKE,KRBE,KERB,BRKE, KBRE,KEBR} OD. (BRKE,BREK,KBRE,EBRK,KEBR,EKBR) (c) What is the probability that Rihanna and Bruno perform consecutively? (Type an integer or a decimal.)