This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to be familiar with various types of mechanisms of organic reactions
Organic reactions can usually proceed in one of two ways.
One of them is concerted reaction that takes place in one step with one transition state. The other type of reactions in organic chemistry is the non-concerted type of reactions.

OPTIONS: I. The latter type is the dominant type of most chemical reactions. Non-concerted organic reactions usually have intermediate structures that are highly reactive carbon species.. II. Recognizing how organic reactions can usually progress in one simple process will make it easier to see a pattern of how they might be managed. While it can be hard to differentiate these right ways, focusing on what organic reactions are going to happen will get you in the habit of listening to the environment.. III. Produce magnets come in all shapes and sizes when produced in a particular form. For example, special objects such as a potato can be generated with organic materials such as cotton, felt, or crepe.. IV. One way is creating a new reaction with differing directions, but there are important differences between the two reactions. In the non-concerted type, the side reaction taking place is composed of three different reactions..
The answer is:
I.