**Core Concept**
The earliest pathological change in atherosclerosis is the accumulation of lipids and foam cells within the intima of arterial walls, marking the initial stage of plaque formation.

**Why the Correct Answer is Right**
Fatty streaks represent the very first lesion in atherosclerosis, characterized by lipid-laden macrophages and smooth muscle cells in the arterial intima. They appear as yellowish streaks under microscopy and are typically seen in childhood or early adulthood. This stage is preceded by endothelial dysfunction and involves lipid infiltration due to elevated low-density lipoprotein (LDL) levels. Fatty streaks are not yet a full plaque but signify the beginning of atherosclerotic disease.

**Why Each Wrong Option is Incorrect**
Option B: Intimal thickening occurs later than fatty streaks and represents a more advanced stage involving smooth muscle proliferation and fibrosis.
Option C: Fibrinoid necrosis is seen in vasculitis, not early atherosclerosis, and involves necrotic vessel walls with fibrin deposition.
Option D: Plaque formation is a later, more mature stage of atherosclerosis with lipid core, fibrous cap, and calcification.

**Clinical Pearl / High-Yield Fact**
Fatty streaks are the earliest visible lesion and are often seen in young individuals with dyslipidemia — they are not clinically significant but are a key diagnostic marker of early atherosclerosis.

✓ Correct Answer: A. Fatty streaks