Giá trị của f'(0) là

A

Ta có \(f'\left( 0 \right) = \mathop {\lim }\limits_{x \to 0} \frac{{f\left( x \right) - f\left( 0 \right)}}{x} = \mathop {\lim }\limits_{x \to 0} \frac{1}{{\left( {x - 1} \right)\left( {x - 2} \right)...\left( {x - 2019} \right)}} = \frac{1}{{\left( { - 1} \right).\left( { - 2} \right)...\left( { - 2019} \right)}} =  - \frac{1}{{2019!}}\).