Which resource led to conflicts between British and Dutch colonialists in Africa?
a. coal
b. crude oil
c. diamonds
d. ivory

The answer in this case would be option c. or diamonds.

Explanation:

The cape colony area in South Africa was traditionally considered as an important center of diamond mining which attracted several European colonialists to settle in the particular area.The mining area came under the dominion of Dutch colonialists and remained as such for quiet a long period of time until the late 18th century.During this time period,it was taken away by the British rulers from the Dutch colonialists through military coercion which was again taken back by the Dutch during the initial 19th century.During the mid and late 19th century,following the discovery of gold and diamond in the concerned region colonial migration increased and led to the exploitation of the local tribes and inhabitants and also further impelled the British-Dutch military conflict which mainly centered on colonial control over the diamond mines and annexation of the concerned mining areas.

The answer is option b and c.