Answer:d.group polarization.
Explanation: Group polarization refers to the fact that when people are in a group which shares similar attitude with them , they are more likely to take decisions that are extreme in nature more than they would if they were taking the decision alone.
They become content to take risky decisions that may even put their own lives in danger, this is if the person had initially thought about this risk then it get more encouraged by the group. For a cautious person when they meet more cautious people they become extremely cautious.
These more extreme decisions are towards greater risk if individuals' initial tendencies are to be risky and towards greater caution if individuals' initial tendencies are to be cautious.