First Principles Thinking: Asset Accumulation
A is correct. The primitive is that Revenue represents value earned, while Cash Received is actual inflow. Accounts Receivable (AR) represents revenue earned but not yet collected. If AR increases (primitive: asset accumulation), it means some of this period's revenue was retained as a claim rather than collected as cash. Therefore, Cash < Revenue. Calculation: $500,000 - 20,000 = 480,000$.
C is incorrect because it adds the increase, implying the company collected the revenue plus extra cash, which describes a decrease in AR (collection of prior debts).
B is incorrect because it ignores the accrual adjustment entirely.