By the late 19th century, the British Empire had a growing presence in what is now modern-day Nigeria. The region was divided into several colonial administrative entities. The Colony of Lagos, which was a British colony since 1861, was one of the key regions under British control, mainly because of its strategic port and access to trade routes.

Protectorate of Southern Nigeria:
- In the 1880s and 1890s, Britain expanded its influence into the interior regions of southern Nigeria by establishing protectorates, which were areas where local rulers retained some autonomy but were effectively under British control.
- In 1900, the British officially formed the Protectorate of Southern Nigeria from previously independent territories and trading companies, consolidating their power over much of the southern part of what would become Nigeria.

Amalgamation in February 1906:
- By February 1906, the British administration sought to simplify governance and improve administrative efficiency. As a result, they amalgamated the Colony of Lagos with the Protectorate of Southern Nigeria to form a single entity called the Colony and Protectorate of Southern Nigeria.
- This was part of a broader strategy of consolidation to streamline British colonial governance in West Africa and to reduce administrative costs.

Outcome:
The amalgamation of Lagos and Southern Nigeria in 1906 served as a precursor to the later amalgamation of Southern Nigeria and Northern Nigeria in 1914, forming what became modern Nigeria. This laid the groundwork for British colonial rule over a unified Nigeria, which continued until the country gained independence in 1960.


The event took place in February 1906 because it was part of Britain's larger strategy of consolidating its colonies and protectorates for easier administration and control.

Thus, the correct answer is D. February 1906.