One opposing claim that Jefferson anticipates is that prudence would "dictate that Governments long established should not be changed for light and transient causes". Indeed, he says, and experience demonstrates that mankind would take all of the suffers, as long they are bearable, before changing the Government to which they are used to. But when a long trail of abuses and usurpations makes that Government despotic and not the system that guarantees the rights of life, liberty and the pursuit of happiness, it is the duty of men to take down that government and establish a new one that guarantees those rights. And so he lists the abuses that the King's ruling has inflicted upon the colonies, such as imposing taxes, cutting off their trade, dissolving Representatives Houses when it didn't follow his wishes, and not re-establishing them after a long time, etc.
Jefferson is trying to demonstrate why it is fair and justifiable that the colonies break free from the English ruling after it didn't stop with its tyrannical actions towards them, when the colonists has petitioned it in the most humble way. If the civilized and lawful approaches weren't enough to reform the regime, then it is fair to take it down and build a new one.
In the body as a reason, is your answer sweetie. This is because the paragraph starts out with the words one explanation which signifies that this would be a reason.
