Hygromycin B, generally used as a selection marker in plant transformation protocols is
The principle of metabolic engineering and inheritance explains that exogenous gene introduction and pathway extension enable trait improvement. Hence an aminoglycoside bacteriocidal antibiotic isolated from the bacterium Strept... fits best because it demonstrates metabolic extension and combinatorial biosynthesis, as documented in authoritative sources on genetics and biotechnology.
Ref: Griffiths et al., Introduction to Genetic Analysis, 11th Edition, Chapter 5, discusses metabolic pathways, recombinant DNA technology, metabolic extension and Golden Rice as pathway engineering for vitamin A production.
