What was the outcome when you had to take a lead in an important project?

Honestly and humbly. If it went well, praise the team as a whole and note your contributions. Do not oversell yourself. If it went poorly, point out what you learned from the experience and how you would do it again. Resist the temptation to place blame on individuals as this reflects negatively on you. If it went kinda well, kinda poorly, mix and match from the above.