Which of the following situation(s) lead to fixation of an allele? model parameters: starting frequency of allele a1: 0.5. starting frequency of allele a2: 0.5. no migration. mutation rate from a1 to a2: 0.001. mutation rate from a2 to a1: 0.001. population size: 100 model parameters: starting frequency of allele a1: 1.0. starting frequency of allele a2: 0.0. fitness of genotype a1a1: 0.7. fitness of genotype a1a2: 0..9. fitness of genotype a2a2: 1.0. mutation rate from a1 to a2: 0.001. mutation rate from a2 to a1: 0.001. no migration. no drift. model parameters: starting frequency of allele a1: 0.5. starting frequency of allele a2: 0.5. fitness of genotype a1a1: 1. fitness of genotype a1a2: 0.9. fitness of genotype a2a2: 0.8. no mutation. fraction of migrants each generation: 0.05. frequency of a1 in source populations: 0.9. no drift model parameters: starting frequency of allele a1: 0.3. starting frequency of allele a2: 0.7. fitness of genotype a1a1: 1.0. fitness of genotype a1a2: 0.8. fitness of genotype a2a2: 0.9. no mutation. fraction of migrants each generation: 0.01. frequency of a1 in source populations: 0.0. no drift.