I got the support word here which is
; and the ideas are supporting but I can not understand the proper semantic for the blank
I got the support word here which is
Yes, there is a support here. Let’s examine the idea in the second part and then come back and answer the blank.
The second part says that the Constitution, a key document for the government, is not lengthy. We should be looking for something to not be lengthy.
In the first part, the statement is that we cannot attribute his political indifference to the tedious ____ of the founders. If we want the idea to suggest that the founders were not lengthy in their writing, then we cannot attribute his political indifference to the tedious (lengthiness) of the country’s founders.
A synonym for lengthiness is volubility (choice D).