In this task, you need to provide the correct option for a given problem on probability from the provided options.

Q: Problem: a box contains 20 electric bulbs , out of which 4 are defective . two bulbs are chosen at random form this box . the probability that at least one of these is defective is : 
Options: a ) 8 / 19 , b ) 7 / 19 , c ) 10 / 19 , d ) 20 / 19 , e ) 22 / 19

A: b
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Q: Problem: in how many ways 3 boys and 3 girls can be seated in a row so that they are alternate . 
Options: a ) 144 , b ) 288 , c ) 36 , d ) 256 , e ) none

A: c
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Q: Problem: a box contains 20 electric bulbs , out of which 4 are defective . two bulbs are chosen at random from this box . the probability that at least one of these is defective is 
Options: a ) 7 / 19 , b ) 6 / 19 , c ) 5 / 19 , d ) 4 / 19 , e ) none of these

A:
a
****