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: Ozone is a molecule containing ____ oxygen atoms.\Question: Choose the right answer from options given a) one b) nine c) no d) three

Answer: d


Question: Alleles fall into ____ classes based on somatic, gonadal and dauer phenotypes.\Question: Choose the right answer from options given a) ten b) six c) eight d) no

Answer: b


Question: Natural erbium is a mixture of ____ stable isotopes .\Question: Choose the right answer from options given a) ten b) six c) one d) zero

Answer:
b