The correct answer is D. The fish would become extinct as they would not be able to reproduce.
Step-by-step explanation:
Fish as most organism prevail over time due to adaptation to environmental conditions and reproduction, in terms of reproduction fish reproduce sexually which means a female gamete and a male gamete are needed to produce offspring, also this, implies both gametes need to be in contact so fertilization can take place. Because of this, if there is a natural or non-natural barrier that stops female and male fish to reunite and therefore prevents the gametes of fish to lead to fertilization and this barrier prevails over time, the species is likely to become extinct or disappear as there are not new individuals or future generations.