<prompt> Chemical messenger acting at long distance in -AutocrineParacrineEndocrineAuto-para-crine  <response>: Ans. is 6c i.e., Endocrine o Hormones are chemical mediators that control cellular functions. They are secreted into the blood stream by ductless endocrine glands and thereby exert widespread actions.o Hormone may have : -i Autocrine action: - Acts on the cell from which it is secreted.ii Paracrine action: - Acts on neighboring cells, e.g., the effect of gastrin on D cells secreting somatostatin.iii Endocrine action: - Acts on cells distant to the cell from which it is secreted. Most of the hormones act by this mechanism. 