I'd like you to correct this sentence.

The more salt or sugar was rubbed on bread, the less chance that mold would grow on them.

I'd like you to correct this sentence.

The more salt or sugar was rubbed on bread, the less mold grew on them.

Option 1:

The more salt or sugar was rubbed on the bread, the less mold grew on it.

Option 2:

The more salt or sugar is rubbed on bread, the less mold grows on it.

I'd like you to correct this sentence.

The more salt or sugar was rubbed on bread, the less mold grew on them.

The appearance of mould on bread was less after the bread had been rubbed with salt or suger.