For me it's understanding the word "whenever". Meaning otherwise as always, every time, each single time, all the time, etc.

Another way to word this is: Every time plant material is mixed into garden soil, the number of beneficial soil bacteria increases.

The 2 concepts: Plant Material Being Mixed (PPM) & Beneficial Social Bacteria Increasing (BBI)

So we know "every time" means it's sufficient. So whenever, or every time, plant material is mixed into garden soil, beneficial soil bacteria increases.

PMM --> BBI

It's sufficient (or enough) information that we can know that every time we mix plant material into the soil, we can expect bacteria to increase. This is because plant material is the subset and bacteria increasing in the superset.

But we cannot go backwards, so I can't say that if beneficial bacteria increases then that means we must have mixed plant material into the soil. The bacteria could have increased for other reasons such as better environment, adding fertilizer, etc. The sentence doesn't tell us that, it only tells us enough (or sufficient) information to know that when(ever) plant material is mixed into garden soil, then beneficial bacteria increases.

I can say however, that if bacteria is not increasing, then I must have not mixed in plant material. Because knowing plant material was mixed in is enough to know bacteria will increase.

IDK if that helps, it's like language gymnastics with rules and you can only go in the direction that meets the rule. It helps me to draw the sub and super sets too. But for this question in particular it is understanding that whenever means every time.

At this point we need a pic of Athena!

That cat is living a good life lol

LOL My assumption was Mr. Fat Cat eats Salmon. Neither of my cats like salmon :)