Tìm \(x\) là số chính phương để \(2019A\) là số nguyên.
A.\(x \in \left\{ {1;\,\,9;\,\,81;\,\,{{2019}^2};\,\,{{6057}^2}} \right\}\)
B.\(x \in \left\{ {2;\,\,16;\,\,100;\,\,{{2020}^2};\,\,{{6058}^2}} \right\}\)
C.\(x \in \left\{ {1;\,\,9;\,\,25;\,\,{{2016}^2};\,\,{{6055}^2}} \right\}\)
D.\(x \in \left\{ {0;\,\,4;\,\,64;\,\,{{2018}^2};\,\,{{6056}^2}} \right\}\)