The people of Southern Nigeria first encountered Europeans through peaceful trade in the 15th century when Portuguese explorers arrived along the West African coast. These early interactions were primarily centred around trade in goods such as spices, cloth, and beads, later expanding to include the transatlantic slave trade. Over time, the British and other European traders also established commercial relations with various ethnic groups, including the Yoruba, Igbo and Efik.

While church missions (B) and gunboat diplomacy (C) played significant roles later—especially in the 19th century during colonial expansion—the earliest interactions were based on trade, making D. peaceful trade the correct choice.