A(n) is the smallest unit of an element that maintains the properties of that element.

question 2 options:

molecule

nucleus

atom

particle

The renown geologist Charles Lyell had brought the concept of "Present is the key to the past" which means that that the geological processes and the activities that are taking place today must have taken place in the past and also concluded that these same geological activities will be taking place in the future too.

So we can make a prediction at any point and further studying this activities we can prepare for the steps that are needed to be taken for the mankind to exist.