A company has a $20 million stock portfolio with a beta of 4.0. It plans to hold the portfolio for one month. The current spot price of the stock market index is $4000. 1-month futures contracts on $250 times the stock index can be traded. What trade is necessary to reduce the portfolio beta to zero?
a Long 80 contracts
b Short 80 contracts
c Long 20 contracts
d Short 20 contracts