Correct Option: B  [ B ]
Remark:
The corrected sentence is: "I saw the blind man (A)/ crossing the busy road (B)/ without any help (C)/ No error (D)."
the word "crossed" is a past tense verb, which
doesn't fit with the context. the verb "crossed" should be "crossing" to show that the man was in the middle of crossing the road when the speaker saw him.