Final answer:
A design with intentionally empty cells in factorial design is known as a Fractional factorial design. Conversely, in a scientific poll design, a leading question is not utilized as it can bias results, while a random sample is essential for representativeness.
Step-by-step explanation:
A design in which some cells or combinations in a factorial design are intentionally left empty is said to be b) Fractional factorial design. A fractional factorial design is a type of experimental design that involves conducting a subset of the possible experiments that would be run in a full factorial design.
This design is used when it's not feasible to run a full factorial experiment due to constraints like time, resources, or money. By using a fractional factorial design, researchers can still estimate most interactions and main effects with fewer experimental runs.
In contrast, a random sample b) a random sample is a key element of a scientific poll design because it ensures that every individual has an equal chance of being selected, promoting the representativeness and validity of the results.