The following graph shows the range of variation among population members for a trait determined by multiple genes. <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/biology/b4d0695bf045571b4f307113d05b0a01-.png" /> If this population is subject to stabilizing selection for several generations, which of the distributions (a-d) is most likely to result?