Communalism is an aggressive political ideology linked to:

Religion

The correct answer is Option (3) → Religion

The word ‘communalism’ refers to aggressive chauvinism based on religious identity. Chauvinism itself is an attitude that sees one’s own group as the only legitimate or worthy group, with other groups being seen – by definition – as inferior, illegitimate and opposed. Thus, to simplify further, communalism is an aggressive political ideology linked to religion.