What should scientist consider when studying tree rungs rings to understand the variations in the local climate

A Scientist would consider the color and the width of tree rings give clues about the past climatic conditions of a place.

Explanation:

Trees are quite sensitive to local climatic conditions like rain, temperature, etc. That is why they tend to be useful for weather experts to judge the climate variations.  There are many clues seen in the rings of the trees that are helpful in studying the local climate.

Some of the clues are obtained by  

The concentric rings tell about the age of the tree and the weather conditions during its life period.  The light - colored rings tells that the tree has grown in the spring and early summer season whereas the dark rings tell that the tree has grown in late summer and during fall.

Moreover, the rings get wider in warm, wet years and get thinner in cold and dry seasons. If the tree has experienced harsh conditions like drought, etc., it will have a hindered growth.

A

patterns in their width, their density, and their composition

c should be the answer