Read the following passage carefully and answer the question that follows:

The Cold War threatened to divide the world into two alliances. Under these circumstances, many of the newly independent countries, after gaining their independence from the colonial powers such as Britain and France, were worried that they would lose their freedom as soon as they gained formal independence. Cracks and splits within the western and eastern alliances were quick to appear headed by the USA and the USSR respectively. Communist China quarrelled with the USSR towards the late 1950s, and, in 1969, they fought a brief war over a territorial dispute.

Which former superpower headed the eastern alliances ?

USSR

The correct answer is option (4) - USSR

As per the passage:

Cracks and splits within the western and eastern alliances were quick to appear headed by the USA and the USSR respectively. Communist China quarrelled with the USSR towards the late 1950s, and, in 1969, they fought a brief war over a territorial dispute.