Six people are riding camels and being led in a straight line across a gently rising sandy slope with mountains in the background, by a man walking and holding the tether of the lead camel.
Many people are lying in the sun at the park.
The people can't be riding Camels while lying in the sun.
You cannot ride camels while lying in the sun.  In addition, the location of at the park and at a gently rising sandy slope is contradictory.
one cannot be riding and lying simultaneously.