The correct option is B Bahar Khan
In 1522 Sher Shah joined under the service of Bahar Khan under Lohani, the ruler of Bihar. His master rewarded him with the title of Sher Khan for his bravery in killing a tiger single-handed. But the intrigues of his enemies compelled him to leave Bihar and he joined the camp of Babur in 1527. After the death of Bahar Khan Lohani , Sher Khan left Mughal service and became the ruler of Bihar.