Which One Is Correct?

Hi, I have a one question

Archaeological fieldwork is the discovery of sites worth studying. Sometimes archaeologists know where to look; however, at other time they make such discoveries by chance. Some objects are close to the surface and can be found easily, while others can only be traced with the help of satellite images or other advanced methods. For acrhaeological sites under the earth's surface or under water, they use sound technology and radar. After fieldwork is completed, an archaeologist starts to excavate the site. They use various instruments like shovels and picks, but must be careful not to damage or destroy valuable objects and findings. Archaeologists use special brushes to scrap away soil and set objects free. The objects they discover are called artefacts, labelled and often covered with chemicals so that they can be preserved. Sometimes field laboratories are set up to catalogue the objects. When finished with digging, archaeologists must interpret what they have found. They try to determine how old artefacts are and from which period they come. Sometimes scientists from other fields help with their work.

2- As pointed out in the passage, archaeological fieldwork is the process of locating places that are worth studying.................. .

A- and it is used in the event that sound technology and radar are not enough

B- but it is being used less and less thanks to satellite images and other advanced methods

C- and it is conducted in different ways by using different methods

D- even though chance is always the most important factor in archaeology

E- due to the fact that archaeologists hardly ever know where to look

My answer is D but I'm not sure