 
<translate> Nsogbu a na-apụta ma ọ bụrụ na ọnụ ọgụgụ ndị bi n'otu ebe ebe belata n'otu ntabi anya. Mmụba nke ọnụ ọgụgụ ndị bi na ya na-ebelata site ná mbata na ọpụpụ nke ndị si mba ọzọ. Mmetụta nkwụsị na-eme na mbugharị mpụga. Ya mere, azịza ikpeazụ bụ (A). <eng> Bottleneck effect occurs when a population suddenly gets much smaller. Population growth is reduced by external migration. Bottleneck effect occurs with external migration. So the final answer is (A). 