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').

Routers are basically systems, which connect ____ networks together.\Question: Choose the right answer from options given a) three b) two c) nine d) six
b

Most herbal formulas contain ____ to twelve herbs in various combinations.\Question: Choose the right answer from options given a) four b) no c) seven d) six
d

Printing presses use a minimum of ____ ink colours to accurately reproduce 'full colour' images.\Question: Choose the right answer from options given a) four b) no c) eight d) nine

a