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').

Q: Angiosperms inhabit all ____ continents, as well as the oceans.\Question: Choose the right answer from options given a) five b) seven c) three d) zero

A: b
****
Q: 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

A: c
****
Q: Erythropoiesis is the process in which new erythrocytes are produced, which takes about ____ days.\Question: Choose the right answer from options given a) four b) seven c) eight d) three

A:
b
****