18. During post-marketing surveillance, a new antibiotic shows a statistically significant increase in the incidence of a rare cardiac arrhythmia. What medicinal epidemiological implication is this?

The drug should be immediately withdrawn from the market without further investigation.
A signal has been detected, prompting further investigation, possibly leading to a black box warning or withdrawal.
The finding is likely due to chance and can be ignored.
The drug is still safe for all patients.

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