Final answer:
The phrase 'when as and if issued' refers to the trading of securities that are expected to be issued, and it is most closely related to the settlement date of those trades.
Step-by-step explanation:
The term "when as and if issued" is commonly associated with the trading of securities that have been announced but not yet issued.
In this context, the correct answer to the question is D. Settlement date. 'When, as, and if issued' trading refers to conditional transactions made on the expectation that securities will be issued in the future.
The actual settlement of the trade—the transfer of ownership and payment for the securities—occurs on the settlement date, which may be uncertain for transactions involving securities traded on a 'when issued' basis.