Option : (D)
Formula :-
(i) A function f(x) is said to be continuous at a point x = a of its domain, if
\(\lim\limits_{x \to a}f(x)\) = f(a)
\(\lim\limits_{x \to a^+}f(a+h)\) = \(\lim\limits_{x \to a^-}f(a-h)\) = f(a)
Given :-
\(f(x) = \begin{cases}5x-4,\quad \text{if}\,0<x≤1\\ 4x^2+3ax,\quad\text{if}\,1<x<2\\\end{cases} \)
Now at x = 1

Therefore discontinuous at x = 3.