The answer is C. At first I thought it was D but it actually belongs to clubmosses
<span>The correct answer is b.0.5 to 1 micrometre thick.</span>
Usually, the respiratory membrane is about 0.6 micrometres thick. This membrane consists of the alveolar epithelial cells, the capillary endothelial cell, and basement membranes which are formed by the alveolar and capillary cells.
Its basically saying something (object) at rest is going to stay there until something moves it like an outside object.