How, According to Abbate, Does a Soldier's Obligation to Obey

How, according to Abbate, does a soldier's obligation to obey lawful orders show that soldiers ought not to assume extra risks to protect civilian casualties?

A) Soldiers have a role-based obligation to abide by lawful orders, even if those orders prohibit the soldier from assuming extra risks to avoid collateral casualties. Therefore, if soldiers are ordered not to assume those risks, they are forbidden to do so.
B) Any order that does not require soldiers to assume extra risks to protect civilians is unlawful. Therefore, soldiers are not obligated to assume those risks.
C) The US Field Manual prohibits soldiers from assuming extra risks to protect civilians. Therefore, soldiers are obligated not to assume extra risks to protect civilians.
D) According to the principles of jus in bello, soldiers operate under a standing order to protect civilians. Therefore, they are obligated to assume any necessary risks to avoid collateral casualties.