Which of the following countries pioneered the establishment of ECOWAS alongside Nigeria?

In April 1972, General Gowon of Nigeria and General Eyadema of Togo re-launched the idea, drew up proposals and toured 12 countries, soliciting their plan from July to August 1973. A meeting was then called at Lomé from 10-15 December 1973, which studied a draft treaty. This was further examined at a meeting of experts and jurists in Accra in January 1974 and by a ministerial meeting in Monrovia in January 1975. Finally, 15 West African countries signed the treaty for an Economic Community of West African States (Treaty of Lagos) on 28 May 1975. The protocols launching ECOWAS were signed in Lomé, Togo, on 5 November 1976. In 1977 Cape Verde joined ECOWAS, while in 2002 Mauritania withdrew form the Community.