Tyrahn’s rods do not transform light into nerve impulses as easily and efficiently as they should, so he has difficulty seeing in dim light. this is called

This is called night blindness. It is also known as nyctalopia and is a vision impairment. This happens when the rods in the eyes do not transform light into the nerve impulses efficiently and easily than normal. As a result you will be having hard time seeing in dark places where there is only minimal light. This is can be caused by cataracts, nearsightedness, usher syndrome or deficiency of vitamin A. These can be cured by certain procedures. To prevent developing this eye problem, it is important to take care of your eyes. You should monitor sugar levels and eat the right foods. Foods that are abundant in vitamin A and other antioxidants would help in preventing it.

The answer would be sand and gravel