单项选择题
A and B are married, and had one house property registered under A’s name. B borrowed 1 million yuan from C and concealed this fact to A. B mortgaged the house to C. When B signed the mortgage contract and registered the mortgage, B illegally used A’s signature and signed for A. Now, A claims that the loan and mortgage contract are invalid.
Which of the following is correct?
A、The mortgage contract is invalid.
B、The loan contract is invalid.
C、A has an obligation for the repayment of 1 million loan because he has joint liability.
D、A may plea for revoking of C’s right to mortgage.