In futures markets an arbitrageur:

a. Usually represents hedge funds and trying to implement sophisticated strategies to earn abnormal returns

b. can buy and sell futures contracts multiple times during the day adding depth and liquidity to the markets

c. can be a funds manager and tries to realise risk-free returns taking advantage of price differentials between different markets

d. can represent a superannuation fund and buys VIX futures anticipating high volatility in coming months