Sentence Correction

Source: Kaplan Diagnostic Test

The Vietnamese artist exhibiting work in the United states reported that one of her artistic challenges had been the former widespread unavailability of paper and canvas in wartime,which she said often forced her to work on matchboxes and scraps of newsprint.
A) her artistic challenges had been the former
B) her artistic challenges had been the formerly
C) her artistic challenges is the former
D) their artistic challenges had been the former
E) their artistic challenges is the former

The OA is [spoiler]( A )[/spoiler].

The explanation is as follows:-[spoiler]"Formerly" suggests that what happened in the past was
simply the widespread nature of the unavailability and not the unavailability itself.[/spoiler]

The explanation is still not clear to me.

Thanks in advance.

"Formerly" is an adverb; they modify adjectives, verbs, and other adverbs, and so that word cannot modify "unavailability." The sense of the sentence is that the unavailability only happened during wartime, which means it ended, so we would want "former" to modify "unavailability."

In many cases, it is stylistically preferable to use commas to separate multiple adjectives modifying the same noun, to make it clearer that they are correctly placed: My swollen, red eyes won't stop itching.

Jim@Grockit wrote:"Formerly" is an adverb; they modify adjectives, verbs, and other adverbs, and so that word cannot modify "unavailability." The sense of the sentence is that the unavailability only happened during wartime, which means it ended, so we would want "former" to modify "unavailability."

In many cases, it is stylistically preferable to use commas to separate multiple adjectives modifying the same noun, to make it clearer that they are correctly placed: My swollen, red eyes won't stop itching.

So,since "unavailability" is a noun,it requires the adjective "former" to modify it.-Grammar Rule

I understand the grammar context but from the meaning context how does (Formerly" suggests that what happened in the past was simply the widespread nature of the unavailability and not the unavailability itself. )

I guess both widespread nature of the unavailability and unavailability are nouns?

FormerLY can only modify "widespread" because it is an adverb.

Formerly widespread unavailability is unavailability that still exists, but used to be more common.

Former widespread unavailability is unavailability that no longer exists, but was widespread when it did.