In the figure shown, which pair of angles must be complementary?


​∠AOC​ and ​∠DOB​

∠AOC​ and∠COD

∠COD and ∠DOB

​∠COB​ and∠AOC
4 rays sharing point O. Ray A O, ray C O, ray D O, and ray B O in that order from left to right. Angle C O B is a right angle. ray D O is between ray C O and B O. Ray A O is on the left of ray C O and is acute.