"Debates over what environmental sustainability means often focus on whether humanmade capital can substitute for natural resources-whether human ingenuity will relax natural resource constraints, as in the past. Whether this will be possible in the future is unknown and, coupled with the risk of catastrophe, favours the position of preserving basic natural assets and the associated flow of ecological services (Human Development Report 2011: 2)."

Was the above quoted remark written in defense of strong sustainability or SMS or both? Explain.