It would be primary since the writer himself is getting the information from a direct source.
The wind is just strong enough to move the sand grains which were sorted by size by the wind. Heavier grains were left in place where as smaller grains were carried away. These grains kept moving till they were concentrated in one place usually up a hill. The grains climb the flat slope on the windward side and then fall off the steep side. The dunes may migrate slowly as this process continues, the grains at the upwind side climb the dune with the help of the wind and then fall down the downwind side.<span>
</span>
1.true
2.true
3.fasle
4.true
5.false
6.true
The correct terms to fill in the blanks would be contracts and dilates. In stressful situations, the sympathetic nervous system contracts the arteries of the circulatory system resulting to the dilation of the pupils of the eyes. Also, during these situations, the blood sugar levels are raised since the hormones for stress kick in to combat the stress which in turn raises the blood sugar.
