The potential of a prolonged outage of TC Energy Corp's TRP.TO Canada-to-U.S. Keystone crude oil pipeline helped underpin oil. By Fergal Smith TORONTO, Dec 12 (Reuters) - Canada's main stock index rose on Monday, clawing back some recent declines at the start of a big week for central bank policy decisions, as higher oil prices supported the energy sector and technology shares climbed. U.S. stock indexes also rose as investors braced for key inflation data on Tuesday and a likely interest rate hike by the Federal Reserve on Wednesday.