In which change can the substance often be recovered back as before?

Correct answer: Physical change

Direct answer: A, physical change. A physical change changes the form or state of a substance while its chemical identity remains the same. Many such changes can be reversed, so the original substance can often be recovered. For example, ice melts into liquid water and water can freeze back into ice; the substance remains H2O. This is why option A is the best answer. Option B, chemical change, generally produces one or more new substances, such as rust from iron, so the original material cannot usually be recovered by a simple physical step. Option C, combustion, is a particular chemical change involving burning and is not the general answer. Option D, fermentation, is another chemical or biological process that forms new products, such as alcohol or acids, so it is not the intended category. The word “often” matters: not every physical change is perfectly reversible, but recovery is commonly possible. Memory cue: same substance after melting, freezing, cutting, or dissolving usually indicates physical change.