Section $1$:

$($A$)$ I believe Brittany Allen is the easiest to change because her awkwardness during the meeting suggests she may be open to a shift in perspective. $($B$)$ Brittany's quiet nature implies that her endorsement of the project could influence the group positively. Being a supportive team member, her backing might ease the resistance from others.

Section $2$:

Subject: Embracing the Exciting Challenge Ahead

Hi Brittany,

I hope this message finds you well. I wanted to reach out and share my enthusiasm for the upcoming project. Your unique insights and perspective are invaluable to the team, and I believe your support can make a significant impact. The CEO's vision is ambitious, but I am confident that with your creative input, we can turn this into an exciting opportunity. Your endorsement would not only contribute to the success of the project but also inspire the team to collaborate more effectively. I$\text{'}$m eager to hear your thoughts and ideas on how we can make this venture a triumph together.

Best,

$[$Your Name$]$

Section $3$:

The two rhetorical techniques employed in the email are:

Positive Reinforcement: This technique involves highlighting the individual's strengths and contributions. In this case, acknowledging Brittany's unique insights and emphasizing her value to the team aims to boost her confidence and create a sense of importance, fostering a more positive attitude towards the project.

Inclusive Language: By using phrases like $"$we$"$ and "together," the email seeks to create a sense of unity and shared responsibility. This technique aims to make Brittany feel a part of the decision$-$making process, emphasizing the collaborative nature of the project and encouraging her to actively contribute to its success.