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: Color codes are ____ digit combinations of letters and numbers that correspond to a specific color.\Question: Choose the right answer from options given a) six b) eight c) seven d) one

Answer: a


Question: Human females have ____ X chromosomes.\Question: Choose the right answer from options given a) two b) six c) one d) eight

Answer: a


Question: Obstructive apnea is a cessation of breathing that last ____ seconds or more.\Question: Choose the right answer from options given a) five b) ten c) three d) nine

Answer:
b