Which of the following best describes a set of conditions under which archaeoastronomers would conclude that an ancient structure was used for astronomical purposes? a. the structure has the same dome shape as modern astronomical observatories. b. they find that, looking out from the center of the building, there are two windows that align with the rise and set points of two bright stars. c. the structure has numerous features indicating alignments with movements of the sun and cultural heritage claimed that the rulers were descendants of the sun. d. the structure consists of lines in the desert that make patterns visible only from high above.