What is the primary difference between an experiment and an observational study?
A. An observational study involves many more people.
B. Observational studies always make correlations.
C. In an experiment, the researcher manipulates a variable.
D. Experiments are always done in a lab.

What is the effect of narrator's word choice on the tone of this passage? the words "my heart shrank within itself" create a fearful tone. the words "wounded his fellow" develop a remorseful tone. the words "struck harsh upon my ears" suggest an irritated tone. the words "better-omened" set a hopeful tone. excerpt from "the cabuliwallah" by rabindranath tagore i was sitting in my study, looking through the accounts, when some one entered, saluting respectfully, and stood before me. it was rahmun the cabuliwallah. at first i did not recognise him. he had no bag, nor the long hair, nor the same vigour that he used to have. but he smiled, and i knew him again. "when did you come, rahmun? " i asked him. "last evening," he said, "i was released from jail." the words struck harsh upon my ears. i had never before talked with one who had wounded his fellow, and my heart shrank within itself when i realised this; for i felt that the day would have been better-omened had he not turned up.