Answer:
D. to document the process of chemical reactions.
Step-by-step explanation:
A chain of custody can be defined as a paper trail containing the chronological order of items of evidence and how they have been handled, controlled, transferred, analyzed, and disposed during the investigation of a case.
This ultimately implies that, a chain of custody contains all the details or informations regarding the investigators (people) who handled, controlled, transferred, analyzed, and disposed an evidence in the course of carrying out investigations on a particular case. The most important and significant part of an investigation is the evidence because it helps to unravel the truth and facts relating to a case. Therefore, it is very important and essential to document and maintain a chain of custody so as to preserve the evidence.
A chemical reaction can be defined as a reaction in which two or more atoms of a chemical element react to form a chemical compound.
Hence, the possible reason a science technician would be taking photographs in the lab is to document the process of chemical reactions by generating pictorial evidences.