Lời giải chi tiết:

\(\begin{array}{l}{\left( {a - 2b} \right)^5} = C_5^0{\left( a \right)^5}{\left( { - 2b} \right)^0} + C_5^1{\left( a \right)^4}{\left( { - 2b} \right)^1} + C_5^2{\left( a \right)^3}{\left( { - 2b} \right)^2}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + C_5^3{\left( a \right)^2}{\left( { - 2b} \right)^3} + C_5^4{\left( a \right)^1}{\left( { - 2b} \right)^4} + C_5^5{\left( a \right)^0}{\left( { - 2b} \right)^5}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = a{x^5} - 10{a^4}b + 40{a^3}{b^2} - 80{a^2}{b^3} + 80a{b^4} - 32{b^5}\end{array}\)

Chọn D.