regular expression

Question

Answer 1

answer is B

with the help of A we cant derive the sting {1}....so fails

look at option C say we put string as (01)(1)...so continuous 1 occure failed..

at D (episolon)(101)(101)(episolon) = that is 101101 so again fails ...

in options A and B you cant get 2 ones continuous....

Comments

just a minor correction i think,

answer should be only B.

the key question here is "set of all string" now you cannot derive {1} which is a valid string according to the given question from option A.

Hence option B.

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ohh! yes ...you are correct...