Madhvendrasinh
Hi, this is an inference question- so any option that cannot be derived from the passage will be eliminated. For A- we certainly cant derive from the passage that what the balance of opinion will favor in the condition of a blockade.
If you spend some time with D- it says "Any trade embargo against Patria would be likely to fail at some time. " this definitely can be derived from the passage bcoz, "A total blockade of Patria’s ports is necessary to an embargo, but such an action would be likely to cause international discord over the embargo." .... no matter what the case is at some point it will cause international discord.
Hope it helps.