For what value of k is the function \(f\left( x \right) = \;\left\{ {\begin{array}{*{20}{c}} {2x + \frac{1}{4},\;\;\;\;\;x < 0}\\ {k,\;\;\;\;\;\;\;x = 0}\\ {{{\left( {x + \frac{1}{2}} \right)}^2},\;\;\;\;\;\;\;x > 0} \end{array}} \right.\) continuous ?
1
\(\frac{1}{4}\)
2
\(\frac{1}{2}\)
3
1
4
2