38. State the amount of digestion (in mm) that might
be expected after 48 hours in a test tube that is
identical to the other 5 test tubes, but at a tem-
perature of 15°C.
(1) less than 2.5 mm
(2) between 2.5 and 4 mm
(3) between 4.0 and 7.5 mm
(4) more than 7.5 mm