In a population which is in Hardy-Weinberg equilibrium, the frequency of a recessive allele for a certain genetic trait
In genetics and biotechnology, metabolic engineering and inheritance dictates that exogenous gene introduction and pathway extension enable trait improvement. Therefore 84% is correct as it demonstrates metabolic extension and combinatorial biosynthesis, supported by mechanistic studies and conserved across related systems.
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.