**Ethers** have the general formula:
AR-OH
BR-O-R' (two alkyl/aryl groups bonded via oxygen)
CR-CO-R'
DR-CHO
Answer & Solution
Correct answer: B. R-O-R' (two alkyl/aryl groups bonded via oxygen)
Ethers: R-O-R' where R, R' are alkyl/aryl groups (same or different). E.g., diethyl ether $(C_2H_5)_2O$, anisole $C_6H_5OCH_3$, THF (cyclic). Generally less reactive than alcohols; used as solvents.