Final answer:
A leading question is not part of a scientific poll design, as it can bias responses, while a random sample is essential to ensure the poll's results are representative of the population. option d.
Step-by-step explanation:
The question provided appears to be in the context of how a scientific poll is designed. One of the key factors in creating a scientific poll is to avoid leading questions, as they may bias the responses and thus not accurately reflect the views of the overall population. Instead, a scientific poll relies on a random sample, where each member of the population has an equal chance of being selected. This ensures that the results are statistically representative of the population being studied.
Considering the options provided, a leading question is not part of a scientific poll design, while a random sample is a fundamental component. Answering this question, option 'a. a leading question' is the correct choice because it represents an element that would compromise the integrity of the poll.