The year $2003$ was celebrated as the $50^{th}$ anniversary of:

Question

$\begin{array}{1 1}\text{a. Discovery of jumping genes by Barbara McClintok} \\ \text{b. Structure of DNA by Watson and Crick} \\ \text{c. Mendel’s law of inheritance} \\ \text{d. Biotechnology by Karry Mullis.} \end{array} $