Which combination of surveillance signals would most strongly suggest that an outbreak has the potential to expand into a wider epidemic?

Increasing case counts across multiple connected communities, rising test positivity rates, and evidence of new transmission chains (cases without known links), indicating widening transmission.

A single index case in a remote area, immediate cessation of testing, and no detection of secondary cases over multiple reporting periods.

Stable low-level case counts within only one household and no changes in mobility or contact patterns in the wider community.

Decreasing healthcare visits for the syndrome, declining laboratory confirmations despite increased testing, and complete absence of secondary transmission.