Raghu, on waking up early in the morning, often complained about back pain. When his pain persisted, he consulted a doctor who advised him to…

Raghu, on waking up early in the morning, often complained about back pain. When his pain persisted, he consulted a doctor who advised him to purchase a good quality orthopedic mattress. That would ensure correct spinal alignment and reduce the back pain. Raghu surveyed the market and purchased a good quality orthopedic mattress. As the price of the mattress was very high, he wanted to avoid paying GST. The shopkeeper suggested that he can do so if he does not take a receipt for the purchase of the mattress. Raghu readily agreed for the same. After few months of using the mattress, his back pain recurred. He realised that the mattress had caved in from the centre. He approached the shopkeeper who refused to entertain Raghu. Raghu wanted to approach the court for redressal of his grievance. However, one of his friends told him that he would not be able to do so as he had not fulfilled one of his responsibilities. From the following, identify the responsibility which Raghu failed to fulfill :