If a particle of mass m is moving with constant velocity v parallel to x-axis in x-y plane as shown in fig. Its angular momentum with respect to origin at any time t will be

• A.                 \[mvb\,\hat{k}\]             
• B.                 \[-mvb\,\hat{k}\]
• C.                 \[mvb\,\hat{i}\]              
• D.                 \[mv\,\hat{i}\]