Answer:
B, A fossil found in rocks from one time period
Explanation:
Fossils are used to determine the ages of rock layers. Index fossils are the most useful for this. Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time. An index fossil allows a scientist to determine the age of the rock it is in. Hope that this helps you :)
 
        
             
        
        
        
Answer:
With an experiment following the scientific method 
Explanation:
The basic steps of the scientific method are: 1) make an observation that describes a problem, 2) create a hypothesis, 3) test the hypothesis, and 4) draw conclusions and refine the hypothesis. Critical thinking is a key component of the scientific method. Without it, you cannot use logic to come to conclusions.
 
        
             
        
        
        
- DNA and RNA are made up of monomers called nucleotides. - DNA and RNA both have 3 nitrogenous bases: Adenine, Cytosine and Guanine. - DNA and RNA both have a phosphate groups in their nucleotides. Sometimes called phosphoric acid.Feb 18, 2009