Answer:
a. a strong hypersensitive response.
b. a high diversity of R proteins.
Explanation:
Hypersenstive response is an immediate defense system in plants because they don't have direct immune system. During an event of pathogen invasion, plant produces reactive radicals (reactive oxygen species, reactive nitrogen species, hydrogen peroxides) to kill the invading pathogen. Therefore, it should be included in the selection of tomato varities against novel biotrophic pathogen as a main criteria.
Further, R proteins are produced by R-genes (resistant genes) that is a defense line in plants against pathogens. Typically, it is known as a Pathogen-Associated Molecular Pattern or PAMP. The presence of r-genes in tomato varieties would help produce enzymes (r-proteins) that will kill or minimize the invador/infection. Hence, it should also be included as a main criterion for the selection of tomato varieties.