Your company has a SQL Azure subscription. You implement a database named Database1. Database1 has two tables named Table1 and Table2. You create a stored procedure named sp1.Sp1 reads data from Table1 and inserts data into Table2. A user named User1 informs you that he is unable to run sp1. You verify that User1 has the SELECT permission on Table1 and Table2. You need to ensure that User1 can run sp1. The solution must minimize the number of permissions assigned to User1. What should you do?
A. Grant User1 the INSERT permission on Table2.
B. Add User1 to the db_datawriter role.
C. Change sp1 to run as the sa user.
D. Grant User1 the EXECUTE permission on sp1.