Changes to prevailing notions about the citizenship rights of blacks, ________ with a redefinition of the role of the government and courts in protecting these rights, continue to ________ the human rights of all Americans, regardless of their skin color.

‘These rights’ in the second clause is a reference to the ‘citizenship rights of blacks’ in the first clause, thereby giving clue for the first blank. As the second clause is in continuation with the first clause and provides support to the first clause, so ‘apportioned’ (to divide and distribute in shares according to plan) in (4) and ‘sundered’ (separate) in (5) can be ruled out. Now, let’s examine the pair words of (1), (2) and (3) for the correct answer. ‘Entrench’ in (1) means to encroach or infringe, which makes no sense and is hence, is ruled out. ‘Exonerate’ in (3) means to relieve of (a burden, obligation); unload. The concept of ‘citizenship rights of blacks’ would not exonerate Americans of their human rights; instead they would ‘bolster’ them up. Hence, (2) is the answer.