1. Social infrastructure primarily consists of elements that contribute to the well-being, quality of life, and social development of a society. While elements like transport, communication, and energy are important for a functioning society, they are typically categorized as economic or physical infrastructure. 
2. Social infrastructure, on the other hand, tends to encompass areas that directly impact the social and human aspects of a society.

Therefore, among the options provided:

(3) Education is the element that is typically included in social infrastructure.