Final answer:
A peer-reviewed scientific journal article is the most reliable source for researching the causes of whale and dolphin strandings, offering credible and well-reviewed information.
Step-by-step explanation:
The most reliable source for a research paper explaining the causes for whale and dolphin strandings during the summer would be b) A peer-reviewed scientific journal article analyzing multiple stranding cases. Such articles are rigorously reviewed by experts in the field before publication, ensuring the information is credible and the research methods are sound. Marine biologists and marine ecologists often engage in studies that are eventually published in such journals, providing insights into the interactions in the ocean, marine populations, and environmental impacts like those causing marine mammal strandings.