Fill in the blank with the correct preposition from the given options:-

The fear that covid-19 has broken ________ again in the world is unfounded.

out

The correct preposition to fill in the blank is "out".

The complete sentence is:

The fear that COVID-19 has broken out again in the world is unfounded.

The preposition "out" is used to indicate that something has started or become known. In this case, it suggests that the fear of COVID-19 has emerged or spread again.