Why did Northern Ireland, Scotland, and Wales gain their own legislatures?

a. The EU ordered that change to take place.

b. The EU ordered that change to take place.

c. The British Parliament had grown too large to be efficient.

d. The two countries gained independence from the UK.

Northern Ireland, Scotland, and Wales gained their own legislatures because c) The British Parliament had grown too large to be efficient. This was also due to the fact that these three places are countries but part of Great Britain (Scotland and Wales) and the United Kingdom (all three countries) and it would only be fair for them to have some say for their own countries specific issues. This process is called devolution.