The correct option is C Sherkhan
Sher Shah Suri ( Sher Khan ) of Bihar and Bengal was a great challenge to Humayun. Sher Khan was consolidating his power in Bihar and Bengal and was emerging as a powerful ruler. He challenged the Mughal rule and even though Humayun was able to temporarily oust Sher Khan from Bengal, he could not defend his territories from Sher Khan for long.