Slump in oil, steel and cement prices presents India with an opportunity to build infrastructure at lower costs as well as shore up public and private spending, Chief Economic Advisor Arvind Subramanian said today.Speaking at the India Investment Summit in Delhi, he said though India faces some headwinds from global slowdown, the country continues to be heaven of macro stability. He said all macroeconomic fundamentals- fiscal deficit, CAD and inflation are strong. He added while external situation pose a challenge in terms of growth, the consolation is that global weaknesses will further strengthen India's economy.Govt has ambitious plan for public investment. Railways, road, irrigation are going to receive high priority. So there is emphasis on domestic investment and international environment has made return on investment actually go up, said Subramanian.