20. Below is an internal control associated with some financial statement audit cycle that the auditors identified for one of their clients. Indicate the control activity that is being considered in question bonder this case. "The president of the company signs the checks once he compares the drawn check against the documents that substantiate the disbursement (underlying documents)."

a. Segregation of tasks (adequate separation of duties)

b. Adequate documents and records

c. Physical controls over assets and records (physical controls)

d. Proper authorization of transactions and activities