Concept:A foreign-policy clash can cause Nigeria to take direct economic action against another country's assets.
Explanation:In 1975, Nigeria strongly supported the MPLA in Angola, led by Agostinho Neto.
Britain backed UNITA, the rival group in the Angolan civil war.
This difference created serious diplomatic tension between Nigeria and Britain.
To show its displeasure, the Murtala/Obasanjo government targeted British business interests.
It therefore nationalised British Petroleum and Barclays Bank in Nigeria.
This meant the Nigerian government took over their ownership and control.
The action was a direct response to Britain's hostile position over Angola.
Option A is impossible because Nigeria is not part of the European Union.
Option B has no link to the Nigeria-Britain dispute of 1975.
Option D refers to an event that does not match this diplomatic crisis.
Answer:C: nationalisation of British petroleum and Barclays bank.