Which of the following trade (s) contain mainly basis risk?

Long 1,000 lots Nov 07 ICE Brent Oil contracts and short 1,000 lots Nov 07 NYMEX

WTI Crude Oil contracts

Long 1,000 lots Nov 07 ICE Brent Oil contracts and long 2,000 lots Nov 07 ICE Brent

Oil at-the-money put

Long1,000 lots Nov 07 ICE Brent Oil contracts and short 1,000 lots Dec 07 ICE Brent

Oil contracts

Long 1,000 lots Nov 07 ICE Brent Oil contracts and short 1,000 lots Dec 07 NYMEX

WTI Crude Oil contracts

这几个哪个存在基差风险呢？