Final answer:
The condition with alternating gray and dark bands is the striated appearance of skeletal muscle tissue, caused by repeating bands of actin and myosin proteins in myofibrils.
Step-by-step explanation:
The condition that has alternating gray bands and dark bands is the striated appearance of skeletal muscle tissue. This appearance is a result of repeating bands of the proteins actin and myosin that are present along the length of myofibrils. The dark bands are called A bands, while the gray bands are called I bands. These bands repeat along myofibrils, giving skeletal muscle tissue its characteristic striated or banded appearance.