The amount of tectonic activity along the margin
.
Explanation:
<u>Margins are categorized as passive when the tectonic activity along it is poor.</u> This is manifested through rare to non-existent <em>earthquakes</em> and <em>volcano eruptions</em> in the area.
On the other hand, <u>active margins are characterized by frequent tectonic activity.</u> This means <em>mountain formation, earthquakes, and volcano activity</em> are not strange here.
