Final answer:
The most effective pattern of organization for a speech about the life of a famous scientist is chronological order, detailing the scientist's life from birth to death and key milestones. Therefore, the correct option is A.
Step-by-step explanation:
The most effective pattern of organization for a speech about the life of a famous scientist would be A. Chronological order. This means detailing the scientist's life from birth to death and key milestones. Organizing the speech in this manner allows for a logical progression of events and helps the audience understand the scientist's journey and development over time.