When a substance has changed into something new or different so that the original substance is gone, as in digestion, radioactive decay, or a battery in a flashlight producing light, it is known as a .

a. physical property
b. chemical property
c. physical change
d. chemical change

d . chemical change.

Explanation:

Physical change involves change which can be retrieved back . sugar is dissolved in water . It is physical change . because sugar can be retrieved by evaporating water.

burning of coal is a chemical change because the ash that we get after burning coal can not be turned into coal .

In the given case in the problem , after digestion , things that  are formed are  quite different . After radioactive decay new element is produced . In battery , current is produced after the chemical reaction which produces new products.

Hence all they involve chemical change.

increases it

i think the answer is a, hope this : )