Option A:
$$37^{371}-26^{371}$$ mod 10
=$$7^{371}-6^{371}$$
Since 7 and 10 are co-prime to each other
E(10) = 10*($$\left(1-\ \frac{\ 1}{2}\right)\left(1-\ \frac{\ 1}{5}\right)$$
=4
$$7^{4}$$ mod 10 = 1
$$7^{4*92}*7^{3}$$ mod 10 = $$1*7^{3}$$ mod 10 =3
$$6^{371}$$ mod 10 = 0
Hence $$37^{371}-26^{371}$$ is not divisible by 10
Option B:
$$37^{371}-26^{371}$$ mod 11
$$4^{371}-4^{371}$$ mod 11
Hence $$37^{371}-26^{371}$$ is divisible by 11
Option C:
$$37^{371}-26^{371}$$ mod 12
$$1^{371}-2^{371}$$ mod 12
Hence $$37^{371}-26^{371}$$ is not divisible by 12
Option D:
$$37^{371}-26^{371}$$ mod 15
$$7^{371}-11^{371}$$ mod 15
$$37^{371}-26^{371}$$ is not divisible by 15
B is the correct answer.
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