Answer: The correct answer for the blank is- A) Sadness.
Human beings are social animals that is they like to be surrounded by other people and share their emotions by means of communication rather than being in isolation.
When they are connected with someone, this means that they share their lives ( including their success, failures, happiness, and all related emotions) with them. In other words, they become attached in various ways such as morally, emotionally, mentally.
Thus, they experience a emotion of sadness when they get separated from other.
