A group of people who speak a common dialect with a particular style, and observe common linguistic norms or scripts is called a

The correct answer is speech community.

A speech community refers to a community or group of people who practice common rules and conventions when speaking the same language. A speech community is unique to particular location or culture, and it factors in people's occupations, age groups, politics, etc. That is why English speakers in south Asia belong to a different speech community compared to English speakers in North America.