Biological membranes are present in all cells, and they make up the endomembrane system of eukaryotic cells. Among other functions, they act as barriers that selectively allow the transport of small molecules and ions into and out of the cell or organelle. Which of the choices best describes a biological membrane

a researcher conducts an experiment on the secretion of a particular hormone in mice. scientists inject mice with a substance that stimulates the production of the hormone. the scientists then test the levels of hormones produced by the mice. the tool used to measure the hormones consistently detects the levels at 10 points lower than the actual hormone levels in the mice. this tool makes measurements, but the measurements aren't .

explanation:

no u

actually the answer is c