[Solved] When relationships between variables differ across geographic units such as counties or across other social settings,researchers say there is ______. A)an association B)emergence C)moderation D)a contextual effect Economically Important: Referring to plants, animals, or minerals that have considerable value or significance to human economies. Cycads: Ancient seed plants with a large crown of compound leaves and a stout trunk, often mistaken for palms or tree ferns. Ginkgo: A member of an ancient gymnosperm group that consists of a single living representative (Ginkgo biloba), a hardy, deciduous tree with broad, fan-shaped leaves and naked, fleshy seeds (on female trees) Nonmotile Sperm: Sperm cells that lack the ability to move or swim, which can affect fertilization capabilities.