Which of the following steps has proven benefit in decreasing puerperal infection following cesarean section?

Prophylactic antibiotics for the cesarean section have been conclusively proven to be beneficial.The first dose is administered at clamping and at least 2 more doses given 8th hourly intravenously in elective cases. Single-dose prophylaxis has been recommended by the ACOG. Both ampicillin and first-generation cephalosporins have been shown to have equal value.(refer to pgno: 436 Sheila 2nd edition )