The rating of given on the name plate of a transformer indicates the:Apparent power which it can supply S=V( supplied voltage)*I (load current) active power = v* i*cosφ reactive power = v* i*sinφ
Answer in official key is “mechanical loss & iron loss ”. Many times stray loss is also considered as total loss actually accured minus calculatable loss. This means loss that can be calculated is known as stray loss.