Which of the phrases (1), (2), (3) and (4) given below the statement should be…

Concept

A sentence-completion question built around a signal word like ‘otherwise’ tests whether you can supply the missing half of a contrast. ‘Otherwise’ signals that whatever follows it must describe a state that is the opposite of, or different in kind from, the state named earlier in the sentence — it does not simply repeat or continue that state.

Application

Here the sentence says the one-and-half-kilometre stretch of potholed road is ‘a black spot on the otherwise ___________ roads.’ Calling it a ‘black spot’ already tells us this stretch is an exception — a bad patch standing out against a background. For ‘otherwise’ to make sense, that background (the rest of the roads) must be described as being in good condition, precisely because the potholed stretch is being singled out as the one bad exception on otherwise good roads. Only ‘smoothly paved roads in ward 155’ describes roads in good condition, so it alone completes the contrast the signal word demands.

Why the other phrases do not fit

• ‘Poorly laid roads in ward 155’ describes roads in bad condition, which matches rather than contrasts with the potholed stretch — it fails to supply the difference in quality that ‘otherwise’ signals.

• ‘General state of roads in ward 155’ is too vague to state whether the roads are good or bad, so it cannot establish the specific contrast that ‘otherwise’ requires.

• ‘Non existent roads in ward 155’ implies there are no roads elsewhere at all, which contradicts describing this particular stretch as a distinct ‘black spot’ standing out against a background of roads that do exist.

So ‘smoothly paved roads in ward 155’ is the only phrase that fits both the grammar and the logical contrast the sentence sets up.