Allen was the surety for the payment of rent by Lear under a lease from Rosenthal Rentals. The lease was for 2 years. A clause in the lease stated that at the expiration of the lease, the lessee had the privilege to renew upon 30 days' prior written notice or, if the lessee remained in possession after its expiration, it was agreed that the lease was to continue for 2 years more. There was a default in the payment of rent during the extended term of the lease and Rosenthal is suing Allen for the rent due based upon the guarantee. Allen contends that he is liable only for the initial term of the lease and not for the extended term. Allen is

A. Not liable since it does not appear that a judgment against Lear has been returned unsatisfied.
B. Not liable because there has been a material alteration of the surety undertaking.
C. Not liable because there was a binding extension of time.
D. Liable on the surety undertaking which would include the additional 2 years.

D. Liable on the surety undertaking which would include the additional 2 years.