A & C is correct.
I have seen a sealed tin of Weightwatchers beans being taken off a cabin crew member at Gatwick because it didn't state the water content on the side of the tin. It had just been through the scanner as well.
A homemade lasagne (in a Pyrex) got through ok though.
Meanwhile, thousands of bottles of water get waved through the security gate after a nominal check and a written confirmation that the load has been security packed at source.
That is what we are up against in the UK. Each UK Airport will have various views on how it applies the basic security rules.
Locals will know the local idiosyncrasies but it is much harder to keep up if you travel around the UK.