问题如下：
Such factors as regulations, competition, and corporate actions relate to:
选项：
A. fund-closure risk.
B. counterparty risk.
C. expectation-related risk.
解释：
A is correct. Fund-closure risk is the risk that an ETF may shut down. The reasons that lead to an ETF closing down often have to do with changes in regulations, increased competition, and corporate activity (merger and acquisition activity within the ETF industry).
