Point B is that any thing that selects for a trait that corresponds to fitness will also select for any traits attached to that trait. Therefore it is really selecting for all the traits, not just the trait that causes increased fitness.
In this way the argument is that natural selection cannot actually select for fitness, it selects for traits that come packaged together- one or two of which cause increased fitness.
Therefore if you apply such a selection over multiple generations you won't necessary end up with an increase in fitness over time because of how these trait packages are passed on hereditarily.
I should point out the contrasting view- which is the current big thing in evolution- "evo-devo"- or evolutionary development- which is trying to mix in pure genetic evolutionary selection with how organisms- particularly brains develop in emybro/first stages of life.
Ther eis a particularly remarkable study on fruitflies which shows that genetically/molecular makeup fruit-flies are basically human- but somewhere a quirk of development drove them into a different path- this quirk is speculated to be related to something that happens during embryo growth/or first few years of life in environment, it reall can't be genetically related.
This has been called the Lego theory- in that life is built of lego blocks and minor quirks one way or other send them spiralling into different directions.
HOWEVER- this is a massive problem for us chemical biologists as we can't find a reason for the lego block theory, there are other- in some ways more efficient- blocks that could have developed, but we're not sure why.
One interesting stud that I actually consulted on involved taking pretty much every chemical reaction known to man, starting with a few simple molecules, then working outwards- reacting them in any reaction that could happen and studying the results. Remarkably energy profiles tended to lead towards biotically relevant molecules though we have no idea why and its something we are thinking about.
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