Under which section must the VA analyze evidence for aggravation of a claimed disability?

The appropriate section for the VA to analyze evidence for aggravation of a claimed disability is found in 38 CFR 3.306. This regulation specifically addresses the considerations for when a pre-existing condition is aggravated by military service. Under this provision, if a veteran has a disability that existed before entering military service, the VA must determine whether that condition worsened during service beyond its natural progression.

The other options relate to different contexts: 38 U.S.C. 1111 pertains primarily to the presumption of soundness upon entry into service, allowing for certain presumptions regarding a veteran's health at the onset of service. 38 U.S.C. 5103 deals with the duty to notify veterans about the information and evidence needed to substantiate a claim, while 38 CFR 3.159 outlines the VA's duty to assist claimants in gathering evidence for their claims. None of these sections specifically address the aggravation of pre-existing disabilities as directly as 38 CFR 3.306 does.