Final answer:
Option D is the most effective telephone communication by the nurse as it offers precise and pertinent patient information, enabling the physician to evaluate the situation urgently.
Step-by-step explanation:
The most effective telephone communication by the nurse is option D. "This is Sheila Ryan on 4100 calling regarding your patient, Mr. Samuels. His BP has dropped from 130/90 at 8 am to 100/70 at 10 am. His pulse has risen from 80 to 100, and he seems restless. He received his 8 am Cardizem." This response is the most professional and provides specific and relevant clinical details necessary for the physician to assess the urgency of the situation.