The first British colonists to settle Australia in large numbers were prisoners. The correct option among all the options given in the question is option "a". The first fleet arrived at the Botany Bay of Australia on 18th of January in the year 1888. As the place seemed unsuitable for living to the commander, so they moved to another place and then ultimately settled at a place called Sydney Cove. The British flag was raised on 26th of January in the year 1788. A total of 751 convicts along with their families came to settle there along with 252 marines and their families.