Correct option is (A) 12 cm
Longest chord in a circle is diameter of the circle.
\(\therefore\) Diameter of circle = 24 cm
\((\because\) Given that longest chord in the circle is 24 cm)
\(\Rightarrow\) 2r = 24 cm
\(\Rightarrow\) r = \(\frac{24}2\) = 12 cm
\(\therefore\) Radius of the circle is 12 cm.
