Answer: Geomatics are referring to the combination of Earth measures with the computer science
Explanation: Now it is a crucial tool for decision-making in many areas such as environmental information systems and natural hazards.
The correct answer is D, because "their" signifie that they are having "their" conversation, and that they own the conversation. C is incorrect because "there" describes where, B is incorrect because "they" describe who, and A is incorrect because "they are" doesn't grammatically or sensibly fit in, so the answer is D.
If I'm correct and if i remember the answer is a. Columbus sighted land in the western hemisphere