First of all, we need to know that it is an infer question. (Yippe! Half way done!)
Premise1: Two actions (international accord + preventing goods from moving in or out of banned country) are NECESSARY for success of embargo.
Premise2: The actions will result in an outcome that will defeat one of the two action which is necessary for the outcome.
Read as: The actions will result in an outcome (total blockade) that (by causing international discord) will defeat one of the two action (international accord) which is necessary for the outcome.
Use 'Prethinking for CR' (a term coined by e-gmat
Logic says that when the prerequisites for an action is killed by outcome of the action, the action may not survive. So, an Embargo which is defeating its NECESSARY requisites will be eventually fail.
We already know the answer at this stage. Still let us check the options
A. 'Shell game' (a term coined by GMAT CR Bible Book)
This is tempting. Our real world knowledge sways away to think that embargo is bad. So, if an embargo fails, it may be favouring Patria!
Wait! Wait ! Wait! What if embargo caused a regime change in Patria and this event paved way for a meritocratic system of governance influence by theory of Übermensch! And then like Germany, Patria became a powerful nation! In this case, embargo might help Patria!!
Am I introducing my personal judgement that embargo is bad? If yes... that is bad habit for CR. Beware!
B. P2 says that international discord will arise. This option negates my P2. At the most, this option create a P3. But in that case also, the argument is left bare without any conclusion/inference.
C. At the most, the option can serve as definition of embargo and may serve as Premise3. Still no sign of conclusion 'shore' for my 'logic ship'.
D. Logical syllogism says that Embargo will fail. This is exactly what we want!
E. In the light of premise1 and 2, this option is self defeating. P2: If blockade is successful, international discord will arise. So, international opinion can never be unanimous.