A convention is best described as: a) A large marketplace for trading b) A legislative meeting c) A large meeting dedicated to a common purpose, organized by a company or association

Option C

Explanation:

In the context of a conference, a convention is indeed a assembly of individuals that occur at an agreed location and time either to address or participate in a mutual interest. The most commonly organised conventions are focused on trade, career and fanbase.

Conventions are mostly organised and managed by skilled gathering and conference managers, sometimes by the event organising company's employees or by independent experts, sometimes in exact description. Many big cities should have a conference centre devoted to organising activities like these.