Which of the following is evidence for tectonic plates?

• A. Fossil records and alignment of magnetic crystals in rocks
• B. They float on the air
• C. Climate data
• D. Ocean salinity

Answer: (A)

Fossil distribution and the magnetization of rocks provide strong evidence that Earth's outer shell is segmented into moving plates. Similar fossils found on now-distant continents suggest those lands were once joined and drifted apart. The alignment of magnetic minerals in rocks records past changes in Earth's magnetic field; as new crust forms at mid-ocean ridges and queens outward, rocks on either side capture symmetric stripes of normal and reversed polarity. This pattern directly matches continual plate movement and seafloor spreading. The other options don’t describe processes tied to plate motion—floating in air isn’t a real phenomenon for rocks, and climate data or ocean salinity reflect atmospheric and oceanic conditions rather than the movement of tectonic plates.