BRISBANE, Australia — Freddie Roach is ready to narrow down Manny Pacquiao’s options following the WBO welterweight championship fight against Jeff Horn: Think about another shot at Floyd Mayweather, or think about retirement. The 11-time world champion is putting his WBO belt on the line Sunday against the 29-year-old Australian, a school teacher who is in the biggest bout of his professional career. “Manny is in a must-win situation.