If it helps, let's rewrite the sentence replacing some possibly difficult words with simpler ones in the context:
First, I'll give definitions of the words I'll be replacing:
a. Moderate in degree or quality; restrained.
b. Exercising moderation and self-restraint.
1. Impossible to stop, alter, or resist; inevitable: an inexorable fate; an inexorable law of nature.
The most obscure word here is "Thermidor", it refers to the month in the new calendar adopted in France during the French Revolution. Of particular note is this association:
On 9 Thermidor Year II (27 July 1794), the French politician
Maximilien Robespierre was denounced by members of the National
Convention as "a tyrant", leading to Robespierre and twenty-one
associates including Louis Antoine de Saint-Just being arrested that
night and beheaded on the following day.
Because of the Thermidorian reaction ... the word "Thermidor" has come
to mean a retreat from more radical goals and strategies during a
revolution, especially when caused by a replacement of leading
So at the end of the sentence we have "a peaceful period of “Thermidor” ensues", or peaceful period of diminished radicalism or extremism. Really you can throw out the reference to Thermidor, because the word "peaceful" does all the explaining that things settle down into a more peaceful state.
So let's rewrite the sentence with the replacements in brackets:
Crane Brinton argued that the middle phases of revolutions are
especially (i) _________ because the unleashed force of social
momentum transfers power [unavoidably] from more stable forces to less
After the first blank it says essentially that a revolution becomes less restrained. Which of the optional words do you think match "less restrained":
- (A) brusque (B) berserk (C) pacific
Yet, he then goes on to say that the excesses (ii)
_________ and a more peaceful period of [diminished extremism] ensues.
Then the author says that after a previous period of unrest and disturbance the revolution settles into a more peaceful condition.
Which of the following words would you associate most with troublesome times (excesses) going away?
- (D) metastasize (E) grow (F) recede
Hope that helped.