When Apurva's views on climate change were favoured by others, she felt that her stance was validated by the public. This phenomenon is known as:

Bandwagon effect

The correct answer is Option (1) → Bandwagon effect

Bandwagon effect: This refers to the tendency for people to adopt certain behaviors, styles, or attitudes simply because others are doing so, regardless of their own independent beliefs. The perception that "everyone else is doing it" or "everyone else agrees" validates one's own position and encourages conformity. In Apurva's case, the public's favor validated her stance, which is the core of the bandwagon effect.

Other Options: 

• Social facilitation: This is the tendency for people to perform simple or well-learned tasks better when in the presence of others. It doesn't directly relate to the validation of one's views.

• Social loafing: This describes the phenomenon of a person exerting less effort to achieve a goal when they work in a group than when they work alone. This is about effort within a group, not validation of views.

• Obedience: This is a form of social influence where an individual acts in response to a direct order from another individual, who is usually an authority figure. This is about following commands, not validation by public opinion.