Given a sentence with a missing word, pick the answer option that best fills out the missing word in the sentence. Indicate each answer with its index ('a', 'b', 'c', 'd').
--------
Question: Water softeners add sodium to drinking water in ____ ways.\Question: Choose the right answer from options given a) zero b) six c) two d) nine

Answer: c


Question: Selenium is ____ times more poisonous than arsenic.\Question: Choose the right answer from options given a) one b) five c) eight d) two

Answer: b


Question: Aortic dissection occurs in ____ forms.\Question: Choose the right answer from options given a) eight b) nine c) seven d) two

Answer:
d