A recent history of customer complaints is a strong supervisory red flag and may cause a firm to place a registered representative on heightened supervision. Heightened supervision is used when a firm identifies increased regulatory, sales-practice, disciplinary, or customer-harm risk associated with a representative. Repeated customer complaints may indicate unsuitable recommendations, unauthorized trading, misrepresentations, excessive trading, poor communication, or other conduct concerns. Choice B is correct. A felony arrest without a charge may require internal review depending on firm policy, but the answer choice is weaker because an arrest alone is not the same as a history of customer-related conduct concerns. A large home equity line of credit is not inherently a securities regulatory red flag. Choice D is not necessarily improper because the account is described as discretionary; if written discretionary authority and supervisory approval exist, the representative is not required to consult the customer before each trade. The SIE outline includes employee conduct, customer complaints, potential red flags, and the consequences of misconduct. It also includes Form U4/U5 reporting, supervisory obligations, and prohibited activities. Reference: Overview of Regulatory Framework; Employee Conduct; Customer Complaints; Potential Red Flags.