Correct option is A
The sweet cherry cultivar 'Lambert' has the S₃S₄ genotype for its S-alleles.
Self-incompatibility in cherries is determined by the S-allele system, where two different S-alleles must be present for pollination to occur.
Lambert cherry is compatible with other cultivars having different S-alleles (like S₁, S₂, etc.) but not with itself.