xpath query

Using postgresql latest for a project.

I have a XML document which I would like to store in a table and query it
using xpath function.

My document looks like this:

<ca>
<c>
<a n="color"><s>red</s></a>
<a n="year"><i>1995</i></a>
</c>
</ca>

How can I extract color. expected value is "red"

Also, is it better to dump the data into a table and then use some sort of
trigger to parse it into a more normalized format for querying or is it
better to to leave it as a XML dump and have the application handle the XML
parsing?

--
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