Larry, Curly, and Moe are working on a class project together. They have been working on the project all afternoon and evening and the deadline is tomorrow. At $2$am Larry suggested that they leave out a required section of the paper, because they don't have enough research to address that aspect of the assignment. Because they are all fatigued and staring down the approaching deadlineCurly and Moe agree to Larry's suggestion. Which of the following conditions gave rise to groupthink in this situation?

group insulation

lack of impartial leadership

similarity of group members

internal and external stress