Carbon dioxide molecules can easily pass through cell membranes due to their small size and nonpolar nature. In contrast, large glycoproteins, chloride ions, and hydrogen ions face barriers because of their size and charge. Therefore, among the listed options, carbon dioxide is the most permeable to cell membranes. ;
The carbon dioxide molecule would most easily pass through a cell membrane due to its small size and nonpolar nature, allowing it to diffuse freely. In contrast, large glycoproteins, chloride ions, and hydrogen ions face barriers due to their size and charge. Therefore, the correct answer is A. Carbon dioxide molecule.
;