A fast-growing and increasingly important geo-political and economic segment of the world is also known asGroup of answer choicesBRICSBREXITperiphery

The fast-growing and increasingly important geopolitical and economic segment of the world referred to in your question is known as BRICS.

BRICS is an acronym for Brazil, Russia, India, China, and South Africa, which are all considered to be at similar stages of newly advanced economic development. This group is noted for its significant influence on regional and global affairs, especially in terms of economic growth and geopolitics.

To summarize:

1. BRICS refers to a group of emerging economies that are pivotal in global economic and political discussions.
2. BREXIT refers to the United Kingdom's exit from the European Union and is not a group of fast-growing economies.
3. Periphery generally refers to countries that are less developed and are often contrasted with developed nations but does not signify a specific geopolitical group like BRICS.

Thus, the correct answer is BRICS.