Both "supporting" and 'to support the" sound okay.
But, I would go with "supporting"
If you don't mind, let me analyze the question a bit.
The committee said it was honored to receive the government grant in support of digitization of old heritage books.
1) in support ofWrong.
GMAT prefers V-A-N (Verb-adjective-Noun). If you can use verb (to support), why don't you use it? Verb always conveys better meaning than the noun does.
2) for supporting theWrong.
"for" is unclear here, why? because "for" is a preposition and can modify a noun or a verb. If it modifies a verb (to receive) ==> "for" means "because" ==> it distorts the meaning. It's like "the committee received the gov grant because of the committee's support the digitization...."
"supporting" is verb-ing modifier.
It modifies a preceding noun "grant" ==> It means the government grant supports the digitization? Nope, the doer who supports the digitization of heritage books is the committee, not the government grant.
4) to support theCorrect. PS: I absolutely agree with Carcass. This is NOT a GMAT-like question for reasons above.
Please +1 KUDO if my post helps. Thank you.
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