Final answer:
The medical assistant's stance of facing the patient and holding her arms at her sides represents an open posture, which is indicative of a willingness to communicate and a non-threatening attitude.
Step-by-step explanation:
A medical assistant who stands facing the patient and holds her arms at her sides while she converses with the patient is demonstrating an open posture. This stance suggests that she is open to communication and willing to engage with the patient. It reflects a non-threatening, welcoming attitude that can help put the patient at ease.
The alternatives such as assertiveness or passive listening may relate to different aspects of communication such as tone of voice or facial expression. An anxious feeling is generally conveyed through behaviors that suggest discomfort, such as fidgeting or avoiding eye contact, which are not described in the scenario. Therefore, based on the information provided, the correct answer is an open posture.