Assume that a point mutation changes the codon auu to auc. why is this a silent mutation?

What do scientific models predict will happen to earth's temperature if current trends continue unmitigated? a. earth will heat and cool in a natural cycle b. earth will heat up and then return to an ice age c. earth will continue to warm at a rate of 0.25 c per decade d. earth will start to cool at a rate of 0.25 c per decade appex