Wild relatives of plant species are a natural and great source for genes for high yield and pest resistance. So, the desired genes coding for high yield can be cloned in the original species. Examples:-
A) Wild rice / Oryza nivara helped in introducing in cultivated rice the trait of high yield.
B) Oryza glaberrima which is generally known as African rice, its gene for the pest resistance protected the cultivated rice from 4 diseases.
So, the correct answer is 'High yield'.