The correct option is A Discovery of gold and diamond in Boer land.
The English had pushed the Boers towards the eastern sides of Africa. Boers settled in the interiors and established free countries for themselves. When gold and diamond mines were discovered in the Boer lands, the British wanted control over the area and this dissatisfied the Boers. They fought two wars called Boer Wars. The English ultimately defeated the Boers and colonised the region.