Read the excerpt from chapter 8 of The Travels of Marco Polo.

Here again good incense grows in profusion—I will tell you how. It is produced by trees of no great size, like little fir trees. They are gashed with knives in various places, and out of these gashes oozes the incense. Some of it even oozes from the tree itself without any gashing, in consequence of the great heat that prevails.

What is most likely the author's purpose for including this detail about Dhofar?

to convince readers of the benefits of using incense from Dhofar
to entertain readers with tales of buying incense
to educate readers about how incense is made in Dhofar
to give readers instructions on how to make their own incense