Which word or phrase adds sensory language to each sentence?
The Hiking Trip

I tightly held onto David's shoulders as he drove his bike over the steep hill. It was a sunny day and the trees were as the last of the snow was finally melting off the pine needles. I had been looking forward to this road trip for a long time. Now that it was happening, I could barely contain my excitement!
The of the bike's engine drowned the sound of the birds chirping and fluttering in the trees. David and I had planned on attempting a long hike into the forest. This would be a new experience for us, but we were more thrilled than nervous. The tour guide had given us clear instructions on ways to prepare ourselves for the hike. One of the instructions was to become physically fitter and stronger. David and I knew how steep the hike would be, and we had decided to go running after work every day till our clothes were soaked with sweat.
It had been a month since then, and we were finally prepared to put our hard work to good use.