Which word can be used to describe someone who is open and sincere in their expressions?

The word "candor" is used to describe the quality of being open, honest, and sincere in expression. When someone exhibits candor, they communicate their thoughts and feelings straightforwardly without any intention to deceive or obscure the truth. This quality is highly valued in interpersonal communication as it fosters trust and transparency.

In contrast, discourse refers to spoken or written communication or debate, but it does not imply sincerity. Eloquent pertains to the ability to express oneself clearly and effectively, often in a way that is persuasive or beautifully crafted, which does not necessarily mean the expression is sincere. Discretion involves the ability to make responsible decisions and to maintain confidentiality, but it does not indicate openness or sincerity. Thus, candor is the most fitting choice to describe someone who is open and sincere in their expressions.