The correct answer is option 'A': Second International.

The Second International, also known as the International Socialist Congress, was formed in Europe in 1889. It was an international body that aimed to coordinate the efforts of socialists all over Europe. The formation of the Second International was a significant development in the history of socialism as it brought together various socialist parties and organizations from different countries, fostering cooperation and solidarity among them.

Below are the key reasons for the formation of the Second International:

1. Growing socialist movement: During the late 19th century, the socialist movement was gaining momentum across Europe. Socialist parties and organizations were forming in different countries, advocating for workers' rights and social justice. The Second International was formed to unite these diverse socialist groups under a common platform.

2. Need for international coordination: Socialists recognized the need for international cooperation to effectively address the issues faced by workers in an increasingly globalized world. The formation of the Second International provided a platform for socialists to exchange ideas, share experiences, and coordinate their activities.

3. Sharing of socialist principles: The Second International aimed to promote the principles of socialism, such as workers' rights, social equality, and opposition to capitalism. By bringing together socialists from different countries, the Second International facilitated the dissemination of these principles and promoted a unified socialist ideology.

4. Solidarity and support: The Second International aimed to foster solidarity among socialists and provide support to workers' struggles in different countries. It organized campaigns, demonstrations, and strikes to champion workers' causes and support their demands for better working conditions, higher wages, and improved social welfare.

5. International congresses: The Second International organized regular congresses where representatives from socialist parties and organizations gathered to discuss and formulate common strategies. These congresses played a crucial role in shaping the socialist movement and promoting international collaboration.

In conclusion, the formation of the Second International in Europe in 1889 was a significant step in the history of socialism. It brought together socialist parties and organizations from different countries, fostering international cooperation, solidarity, and the promotion of socialist principles. The Second International played a crucial role in coordinating the efforts of socialists all over Europe and advocating for workers' rights and social justice.