The meaning of the sentence hangs on a balance which is the following

The same damages you could have by huge distress are similar to those that you could occur following physical trauma.

These are the two parts of the sentence.

If you have a trauma, then you lose something. If you have distressed you lose something as well.

The sentence is built upon a similarity

Why is it not pervasive for the first blank; the rest of the sentence says that amnesia is severe and complete.

Blank (i): devastating
- Context: The phenomenon is described as "rare" and the memory loss can be "as ________as that induced by trauma." The overall tone is serious and negative.
- Fit: The phenomenon is described as causing sudden, severe memory loss, which is highly detrimental to the patient. Devastating (highly destructive or damaging) fits the extreme negative context.
- Venial means easily excused or pardonable (the opposite of what is implied).
- Pervasive means spreading widely throughout an area or group (describes frequency, not impact).

Blank (ii): complete
- Context: The phrase "memory loss can be as ______ as that induced by trauma" sets up a Support/Comparison relationship. The memory loss must be described by an extreme adjective.
- Fit: The key is the comparison. If the amnesia is shocking (Blank i), the memory loss itself must be total or absolute. Complete (having all the necessary or appropriate parts; entire) means the memory loss is total, which matches the severity implied by the trauma comparison.
- Generic (characteristic of a whole group) and limited (restricted) contrast with the necessary tone of severity.


Blank (iii): physical
- Context: The sentence is comparing the memory loss from stress-induced amnesia (a mental/psychological cause) to the memory loss induced by ________ trauma.
- Fit: To create a meaningful and comprehensive comparison (as is common in the GRE), the comparison must be between two distinct types of trauma that produce the same extreme result (complete memory loss). The most logical contrast to stress (psychological/mental trauma) is physical trauma (like a head injury).
- Unexpected describes timing (already used in the first clause implicitly).
- Mental would be redundant with "stress-induced."

The completed sentence reads:

Stress-induced amnesia is a rare and devastating phenomenon; it strikes the patient apparently without warning and the memory loss can be as complete as that induced by physical trauma.