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Multiple choice
Tsirelson's bound on the CHSH operator follows from B4+[A0,A1][B0,B1]|\langle B\rangle| \le \sqrt{4 + \langle[A_0,A_1]\rangle\langle[B_0,B_1]\rangle}, where A0,A1A_0,A_1 and B0,B1B_0,B_1 are dichotomic (±1\pm 1) observables. For ideal anticommuting observables each commutator has operator norm 2, so the product term is 22=42 \cdot 2 = 4. What is the resulting maximum B|\langle B\rangle|?