The correct answer is (b). Pasteurization of milk is done at 62.8° C for 30 minutes. This is the minimum temperature and time required to kill harmful bacteria in milk without significantly affecting its taste or nutritional value.
(a) 54° C for 30 minutes is not a standard pasteurization temperature. It is possible that this temperature and time combination would kill some harmful bacteria, but it is not guaranteed.
(c) 72° C for 32 minutes is a standard pasteurization temperature, but the time required is longer than necessary. This would result in a longer heating process, which could affect the taste and nutritional value of the milk.
(d) 100° C for 10 minutes is a standard boiling temperature. This would kill all harmful bacteria in the milk, but it would also significantly affect the taste and nutritional value of the milk.