If a plant shows the tall trait, what can its genetic combination be?

Correct answer: Two dominant alleles or one dominant and one recessive allele

In a simple Mendelian example, tallness is treated as the dominant trait and dwarfness as recessive. If T represents tallness and t represents dwarfness, a tall plant may have TT or Tt. In both combinations, at least one dominant T allele is present and the tall phenotype appears. Only tt produces a dwarf plant, so option B is correct; the other choices either describe the recessive condition or are biologically impossible.