Question

3 the two men started up the street, arm in arm. the man from the west, his egotism enlarged by success, was beginning to outline the history of his career. the other, submerged in his overcoat, listened with interest.
at the corner stood a drug store, brilliant with electric lights. when they came into this glare each of them turned simultaneously to gaze upon the others face.
the man from the west stopped suddenly and released his arm.
\youre not jimmy wells,\ he snapped. \twenty years is a long time, but not long enough to change a mans nose from a roman to a pug.\
\it sometimes changes a good man into a bad one,\ said the tall man. \youve been under arrest for ten minutes, silky bob. chicago thinks you may have dropped over our way and wires us she wants to have a chat with you. going quietly, are you? thats sensible. now, before we go on to the station heres a note i was asked to hand you. you may read it here at the window. its from patrolman wells.\
the man from the west unfolded the little piece of paper handed him. his hand was steady when he began to read, but it trembled a little by the time he had finished. the note was rather short.
how does silky bob know that the plain clothes policeman is not his friend, jimmy wells?
in the bright lights, silky bob sees that the tall mans nose is not shaped like jimmys.
the plain clothes policeman arrests silky bob as soon as they meet on the street.
in the dark shadows, it was hard for silky bob to see the tall man clearly.
the plain clothes policeman does a bad job pretending to be jimmy.

Explanation:

Silky Bob notices that the plain - clothes policeman's nose is different from Jimmy's. He says, "Twenty years is a long time, but not long enough to change a man's nose from a Roman to a pug." This indicates that he uses the physical feature (nose shape) to determine that the man is not Jimmy.

Answer:

In the bright lights, Silky Bob sees that the tall man's nose is not shaped like Jimmy's.