Which economic factor was a major influence behind the 1914 amalgamation?

Note: The marked answer may not be the primary economic factor. Northern Nigeria had major financial deficits and couldn’t pay for itself. The South had profitable export taxes from palm oil and cocoa.

Amalgamation let the wealthy South subsidize the poor North. Currency unification was a benefit but not the main motivation. Railways helped but weren’t the driving economic reason.

Britain wanted one profitable colony instead of two separate administrations. Combining them reduced administrative costs while boosting overall revenue.