Crude oil prices have climbed sharply amid continuing tensions in the Gulf, raising concerns for investors even as the underlying demand and earnings outlook remains strong. Manish Sonthalia, Director & Chief Investment Officer at Emkay Investment Managers Ltd., said his base-case scenario for Brent crude is $90 a barrel, while an RBI rate hike and Brent crude reaching $120 a barrel could be possible triggers for the market going ahead.