Đáp án đúng: C
Giải chi tiết:\(\begin{array}{l}\,\,\,{3^{x - 1}} + {5.3^{x - 1}} = 162\\\,\,\,\,\,\,\,\,{3^{x - 1}}.\left( {1 + 5} \right)\,\,\,\, = 162\\\,\,\,\,\,\,\,\,\,\,\,\,\,{6.3^{x - 1}}\,\,\,\,\,\,\,\,\,\, = 162\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{3^{x - 1}}\,\,\,\,\,\,\,\,\,\, = 27\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{3^{x - 1}}\,\,\,\,\,\,\,\,\,\, = {3^3}\\ \Rightarrow x - 1 = 3\\ \Rightarrow x = 3 + 1\\ \Rightarrow x = 4\,\,\,\,\left( {tm} \right)\end{array}\)
Vậy \(x = 4\).
Chọn C.