The presentation here seems to fit that of mesenteric vascular occlusion- postprandial pain that lasts 1 hour, food aversion, weight loss. The patient also has risk factors associated with mesenteric vascular occlusion- older than 60 years old, Hyperlipidemia, Hypertension, PMHx.

"The mesenteric circulation consists of three primary vessels that supply blood to the small and large bowel: the celiac artery, superior mesenteric artery (SMA), and inferior mesenteric artery (IMA). Blood flow through these arteries increases within an hour after eating due to an increase in metabolic demand of the intestinal mucosa.Chronic occlusion of a single vessel allows collateral blood flow to compensate, thus symptoms do not typically present until at least two primary vessels are occluded." https://www.ncbi.nlm.nih.gov/books/NBK430748/

Collaterals between SMA and IMA near the splenic flexure (Meandering Mesenteric artery). There is also collateral between Celiac Artery and SMA (Pancreaticoduodenal arcade).

Lastly, I know that there is a 3-cm ectatic aorta found on CT, but an aortic aneurysm would not produce these symptoms. Even if you thought that the symptoms were due to the AAA, you could still get to the correct answer if you use fahmed14's reasoning.

The 3-cm ectatic aorta means she has an abdominal aortic aneurysm. Generally, they tend to occur below the renal branches so I went with the two closest branches- SMA (slightly above renal) and IMA (below renal). Also, splenic flexure is a common watershed area supplied by SMA and IMA so involvement of both can cause her symptoms

the only thing made me choose IMA and SMA is the fact they supply the intestine which is the common site for ischemic mesenteric disease.

all the other vessels, either have collateral supplies or they supply to organs with multiple sources of blood supply

IMA and SMA both have collaterals with each other (marginal arteries and meandering arteries), so incase there is involvement of one of the arteries the blood supply from other can prevent ischemia.

but if both SMA and IMA are involved it would result in ischemia and symptoms described in the question.

looking back at this Q I notice that the patient also has hypertension ...could that have been a clue to include the SMA bc its so close to the renal arteries (Renal a stenosis)?

Why are the IMA and SMA most likely to be affected in her condition?

if the option had SMA and celiac trunk, would that be correct?

One way to look at this would be to go back to pathogenesis of fatty streaks. They are most commonly found at the aortic bifurcation, so basically the lower down you go down the abdominal aorta, more turbulent the flow, causing higher potential for atherosclerosis and stenosis of branch vessels. Also, renal artery stenosis is well described which is given off after the celiac trunk so safe to say celiac trunk is spared in any kind of atherosclerotic stenosis.

Chronic Mesenteric Ischemia aka intestinal angina. Main clues are postprangial epigastric pain, weight loss. Usually due to Celiac (a), SMA, or IMA atherosclerosis.