Answer:
C. In addition to being advantageous the allele also exhibits overdominance.
Explanation:
If the allele is advantageous and dominant over the other alleles, the individuals who own it will adapt better to the environment and most of their offspring will exhibit the attributes granted by the allele, which would increase its frequency in the population over time. In addition, individuals who own it will be more successful and more likely to reproduce than those who do not.