est studied predator-prey relationship in the world. For over sixty years biologists have been watching the island's moose and wolf populations, recording but not interfering in their struggles. But now, the wolf population is doomed and the delicate island ecosystem is spinning out of balance. It is time for NPS scientists to put down their notebooks and step in. It is time to save the wolves, and save the island. What is the main function of the sentence “It is time for NPS scientists to put down their notebooks and step in," in the paragraph? It helps set the tone. It introduces the topic / provides background information, It hooks the reader It presents the thesis.