Determine the term - lowering of stresses
Due to creep of concrete, these compressive strains keep on increasing with time. it means that the length of the member keeps on reducing with time (though this length decrease shall be a of a small magnitude and shall not be visible). Due to this length decrease, length of tendons also shall decrease by the same amount - leading to lowering of stresses in tendons, or in other words, to loss of prestress.