IMO B

imo A.

'principle of all...' is ambiguous. 'principle that all..' is much clearer. 'has been' and 'was' both could be OK. The only distinction is whether the principle is enforced now in its complete sense. However this is not the gist of the statement here. 'is' however is not justified at all for obvious reasons. 'will be necessary..' is wrong as the statement is talking about facts not predictions. 'to be necessary' infinitive is not idiomatic, again when talking about facts.

OA is A

Nice explanation, ov25 - and a great question here.

Just a few things to add since I've seen a fair amount of confusion on here about verb tenses...

-Look at the phrase "as long ago as 1880" - "as long ago as" is setting the stage that our furthest-in-the-past starting point is 1880 but that the beginning of the "nearly a century of adjudication" could have started in 1880 or any point after. In thinking about a timeline, which I suggest you do when you're choosing between verb tenses, it's really helpful to look at these kinds of clues.

-The word "although" is a pretty good clue here, too, and sets up the past-perfect nicely. "Although" here sets up that, even though one past-tense event seems like it would have been sufficient, a much longer series of events had to happen over time.

-It's a little subtle but you can use the term "principle" to tip you off that the indicative tense "must be drawn" is necessary here and that the present-tense "juries being" is incorrect. A principle is something that stands over time..."all men are created equal"; "every action has an equal and opposite reaction"; etc. A principle isn't fleeting and temporary.