Sentence Correction

neeti2711 wrote:
Is B incorrect because the word "demand" requires "that" (command subjunctive) and B violates this rule?!

Source: Manhattan Review

Yes!

gmat_hunt wrote:
Let's know the rule first:
1. COMMA+VERB-ING:
When we use "CLAUSE+COMMA+VERB-ING", the verb-ing modifies the SUBJECT of the previous clause.
Example:
The author helped the poor, giving them money.
=> Giving modifies "The author". Who gave money to the poor? The author.
Now, form B, as it is, meant "Soviet communist state demand it(state)....". Does it make sense? --> State is demanding itself.

In this particular SC, this is not at all a decision point since a case can be made that B is not COMMA+VERB-ING but NOUN VERB-ING;
i.e, COMMA is a part of , Jozef Pilsudski construction.
B)Soviet communist state was routed by the Polish General, Jozef Pilsudski, demanding it to push back its borders east of Vilnius.

gmat_hunt wrote:
2. The intended meaning of the sentence is "Pilsudski demanded it..."; therefore, to refer to the person, we need to use
relative pronoun "WHO" and then add the verb. Here Pilsudski is the antecedent and who is the relative pronoun.
B violates this rule as well.
hope it helps.

who+ verb is not the only way to refer to a person( modify a person).
It is perfectly acceptable to modify a person with Verbing.
However, that and which cannot modify a person.

Only viable reason to eliminate B is that demand cannot take infinitive.
There exist bossy words that can take both subjunctive and infinitive.
order is one such bossy word that can take both infinitive and subjunctive.
demand, however, cannot.
Thus, for those bossy words that can take both, we should look for some other decision point and demand is not one of those bossy words.