What best explains why you should use transitions when writing an argument?

transitions engage and interest the reader in the argument’s subject matter.
transitions clarify the central argument for the reader.
transitions the reader understand how the ideas in the argument are connected.
transitions make reading an argument smoother and more enjoyable.

Interest groups representing businesses and investors are often among the most successful lobbying groups for all of the following reasons, except a. such groups have the financial resources to mount sustained campaigns on their own behalf b. these groups' members contribute heavily to many legislators' campaigns and in so doing gain greater access to legislators c. these groups have often been in existence for decades, allowing them to both master the legislative system and develop close ties with legislators d. the members of these groups make up the majority of voters in many districts