Final answer:
The text that uses a sequential text structure is the one that introduces planets in the order they were discovered, as it follows a chronological sequence.
Step-by-step explanation:
The text about the solar system that most clearly uses a sequential text structure is 'A website that introduces the planets in the order they were discovered'. A sequential text structure is defined by the information being presented in a sequence, whether it be chronological, numerical, or in a clear step-by-step process. In this context, introducing the planets by their order of discovery follows a chronological sequence, thus making it an example of sequential text structure. On the other hand, describing the story behind each planet's name, grouping planets based on similar features, or discussing the moons of Jupiter does not adhere to a strict sequence in the way that the order of discovery does.