Which punctuation mark is required an introduction phrase

"the trouble is," sighed the doctor, grasping her meaning intuitively, "that youth is given up to illusions. it seems to be a provision of nature; a decoy to secure mothers for the race. and nature takes no account of moral consequences, of arbitrary conditions which we create, and which we feel obliged to maintain at any cost." what larger idea is the doctor referring to when he says that nature takes no account of moral consequences? impulses often overrule a person’s sense of good and bad. nature forces women into motherhood. young people are prone to having delusions. morals play no role when we choose who we love.

The development of new inventions in the field of space travel seemed rapid. how does the word rapid function in a sentence?

What is imagery in a play? o o o o a figure of speech that makes a comparison between two different things a literary device that uses vivid language that appeals to the senses a figure of speech in which objects, such as trees, have human attributes a literary device that uses things like animals to express abstract ideas