An oil producer discovers an oil supply in Texas that can be pumped for a profit of $50 per barrel now, $60 per barrel in three years, $80 per barrel in five years, or $90 a barrel in seven years. The current market rate of interest is 3 percent. When should the oil producer extract the oil to obtain the most profit per barrel in present value terms? 

Today 

Three years 

Five years 

Seven years