Final Answer:
The most popularly used criterion for measuring the external effectiveness of a strategic communications plan is B. audience engagement.
Step-by-step explanation:
Effectively measuring the external impact of a strategic communications plan is essential for its success.
Audience engagement stands out as a crucial criterion for evaluating this impact.
This involves assessing how well the communication plan resonates with the target audience, whether it sparks interest, and if it encourages interaction.
Audience engagement is a comprehensive metric that goes beyond mere reach or exposure.
It delves into the qualitative aspects of communication effectiveness, considering factors like audience response, feedback, and the extent to which the message influences perceptions and behaviors.
In today's digital age, metrics such as social media interactions, comments, and shares play a significant role in gauging audience engagement.
By focusing on audience engagement, organizations can gain insights into the effectiveness of their strategic communication in building connections, fostering understanding, and eliciting the desired responses from the target audience.
This criterion provides a holistic view of how well the communication plan achieves its intended goals in the external environment.
In conclusion, the most popularly used criterion for measuring the external effectiveness of a strategic communications plan is audience engagement, offering a nuanced understanding of the plan's impact on the intended audience.