Thumb rules -

1. Infinitives express intentions (to...)
2. Participles express results (-ing)

Now coming to the sentence -

In recent years, international environmental protection groups have claimed credit for the slowing of the depletion of the ozone layer, saying that their push for laws banning the use of CFCs in aerosol cans is helping to preserve this crucial part of our ecosystem.

banning the use of CFCs in aerosol cans is helping

to ban the use of CFCs in aerosol cans is helping

As the sentence talks about claim of a group, hence we are not sure of if the laws actually achieved their purpose or not. But we certainly know the intention/purpose of the laws,
Hence infinitive should be used.

confuse mind wrote:In recent years, international environmental protection groups have claimed credit for the slowing of the depletion of the ozone layer, saying that their push for laws banning the use of CFCs in aerosol cans is helping to preserve this crucial part of our ecosystem.

banning the use of CFCs in aerosol cans is helping

to ban the use of CFCs in aerosol cans is helping


Confused between the above 2 choices, please explain.
The rest other were clear eliminations and thus not quoting here.

OA - [spoiler]1. I marked 2 because the purpose of the law is to ban and thus infinitive form should be used, No?[/spoiler]

Case 1: their push for laws BANNING the use of CFCs.
Here, banning serves as an adjective modifying laws.
A VERBIng modifier serving as an adjective implies CONTEMPORANEOUS action.
In other words, the BANNING is happening RIGHT NOW -- at the same time as the SLOWING of the depletion of the ozone layer.

Case 2: their push for laws TO BAN the use of CFCs.
Here, to ban serves as an adjective modifying laws.
As infinitive serving as an adjective implies POTENTIAL action.
In other words, there is a push for laws TO BAN the use of CFCs, but the ban is not yet in effect.

The international environmental groups HAVE CLAIMED CREDIT for the slowing of the depletion of the ozone layer.
Moreover, their push for laws...IS HELPING to preserve...the ecosystem.
The implication is that -- at least in some parts of the world -- laws BANNING the use of CFCs are already in effect.
Thus, case 1 better conveys the intended meaning: