Explanation
A technician should handle personal communication while on site in a professional and respectful manner. According to the CompTIA A+ Core 2 (220-1102) exam objectives, one of the best practices for communication skills is to "avoid distractions and interruptions" when working with customers1. This means that the technician should not respond to calls and text messages that are not related to the work or the customer, unless there is an emergency situation that requires a response. Responding to personal communication while on site can be seen as rude, unprofessional, and disrespectful to the customer and their time. It can also affect the quality and efficiency of the technician's work and cause errors or delays.
Therefore, the technician should only respond to calls and text messages when an emergency situation requires a response, and inform the customer about the situation and apologize for the interruption.
The other options are not appropriate for handling personal communication while on site. Responding to calls and text messages while on site but not when working directly with personnel (A) is still distracting and unprofessional, as it can interfere with the technician's focus and productivity. Responding to calls and text messages only from family (B) is not a valid criterion, as the technician may receive calls and text messages from other sources that are not related to the work or the customer. Responding to calls and text messages discreetly while on site (D) is not a good practice, as it can still be noticed by the customer or other personnel and create a negative impression.
References:
1: CompTIA A+ Certification Exam Core 2 Objectives - CompTIA