The parliament of a certain country intends to discuss seven bills in four days. The discussion arrangement must meet the following conditions: a maximum of three bills per day; bill four must be placed on the second day; bill one and bill five are discussed on the same day; Proposal No.4 was discussed after Proposal No.2 and before Proposal No.3; Proposal No.3 was discussed before Proposal No.1 and after Proposal No.6. Which two of the following motions can be discussed on the first day? ['bill 6 and bill 7.', 'bill 2 and bill 3.', 'bill two and bill five.', 'bills 5 and 7.']