The correct answer is B) The transformer connections must be made as before with regard to the indicated polarity. When replacing a defective transformer in a paralleled transformer configuration, it is crucial to ensure that the new transformer is connected with the same polarity as the original. This is necessary to maintain the proper phase relationship and avoid circulating currents between the transformers, which could lead to overheating and potential damage to the equipment. Maintaining the indicated polarity is a standard practice and a requirement in the operation of paralleled transformer configurations. The other options are incorrect because: A) Flashing the iron core is not necessary when replacing a transformer, B) Grounding the secondary leads or the iron core is not required for this specific task, and C) Grounding the iron core to remove residual magnetism is also not necessary for this procedure.