Answer:
The answer is Option C: Index fossils.
Explanation:
Index fossils are used to identify geologic periods or faunal stages in rock layers. These fossils must have a wide geographic distribution and manifest obvious evolutionary trends to help geologists and others who need this geological data to better understand the time scale and to pinpoint a time period. For example, ammonites were common during the Mesozoic Era, but they were extinct by the Cretaceous period. Geologists would use ammonites to help determine this time frame if present.
Emperors in Russia were called tsars.
People use what they call Deep winter greenhouses to grow vegetables and other plants year around. They use winter's natural light to grow the plants and some use different kinds of technology to better help the process of growing plants year around.
