Final answer:
All of these represent applied research.
This correct answer is d.
Step-by-step explanation:
The answer to this question is option d. All of these represent applied research.
Applied research is a type of research that aims to solve practical problems or develop new products. It involves using existing knowledge to make advancements and improvements.
In the given options, all of them involve the introduction of new products or vaccines, which require research and development to create and bring them to market.
This correct answer is d.