A3. What is the value of the expression $2019^{3}-3 \cdot 2019 \cdot 2018-2018^{3}$?

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(A) -1
(B) 0
(C) 1
(D) 2018
(E) 2019
A3. Choose $2019^{3}-3 \cdot 2019 \cdot 2018-2018^{3}=2019^{3}-3 \cdot 2019 \cdot 2018 \cdot(2019-2018)-2018^{3}=$ $2019^{3}-3 \cdot 2019^{2} \cdot 2018+3 \cdot 2019 \cdot 2018^{2}-2018^{3}=(2019-2018)^{3}=1$.