Alex Burl is an investment advisor at Helpful Investments, a local investment advisory firm. Helpful Investments requires its employees to invest in the same stocks which Helpful Investments recommends to its clients. Helpful Investments also has established strict procedures determining when trades can be executed in its employees' own portfolios to avoid any conflict of interests with its clients. This procedure is most likely in place to help Burl avoid violations of the Standards of Professional Conduct relating to:（）
A. only material non-public information.
B. only priority of transactions.
C. both independence and material non-public information.