Building a Raised Bed

Hi!  I'm looking to start a small vegetable garden in my apartment's yard, and I'm wondering if anyone has input on building the raised bed (I'm also very new to this website but I saw a lot of good advice!).  It's only going to be 4x4ft (12 inches tall), so I'm hoping it will be alright to use 1-inch thick boards because I'm on a bit of a budget, and 4x4x12in doesn't seem like it would be too much soil weight on the sides.

My main question is if it would be better to attach the boards to each other at the corner (every-other, as in figure A) or to a post (as in figure B).  (For clarification, the bed would be three planks tall either way, I just didn't want to draw all three levels of planks in MS Paint).

The post seems sturdier, but I've heard that because the soil is pushing outwards, it's essentially pulling out the nails slowly because the nails are attached in the same direction as the soil pushes.  Whereas I think varying the boards as in figure A would mean that the soil doesn't pull on the nails the same way due to the varying directions, although I'm really not sure.  If anyone has insight on this (or how big of a post to use for figure B), that would be amazing!

I'm also not sure on wood type.  Cedar wood is a bit expensive for me at the moment, and I'm not even sure how long I'll be staying in my current apartment to keep this bed, so it's alright if it's temporary as long as it doesn't really affect my actual plants.  I'm looking between knotty pine wood and what the store calls SPF (spruce/pine/fir) wood.  I know everyone recommends pine as the budget wood option for garden beds, but I can't tell if that applies to SPF wood.  There is somewhat of a price difference (it would probably cost around $65 to build it with the knotty pine and around $30 with the SPF), but if SPF is really that much of a problem then I can definitely opt for the pine, it's far more reasonable to me than buying cedar at this point in my life.

Also, is it important to cover the insides of the wood with some sort of liner to stop soil from seeping in, or does it not really matter?

Thank you for reading and (in advance) for the help!