What are some of the major reasons for the growth of Regional Trade Agreements?

Cultural similarity, administrative efficiencies, technology enhancements, and supply chain leverage.

Cultural similarity, geographic proximity, security, and supply chain l$$verage$.$

Geographic proximity, similar languages, similar topography, and security.

Security, common currencies, shorter logistical movement of goods, and socialism.

Supply chain leverage, administrative efficiencies, climate change, and geographic proximity.