Which of the following is not a relevant consideration for a trader desirous of delta...

The greater the rebalancing frequency, the more effective the hedge. But the higher the rebalancing frequency (ie the how often the hedge is true-ed up as a response to changes in the market), higher are the transaction costs. Higher transaction costs reduce hedge performance. Therefore transaction costs limit the ability of traders to continuously trade and keep delta at or close to zero. Transaction costs include a number of elements, including market impact costs, dollar costs per trade, and the bid-offer spread on the security.

Traders have to strike a balance between transaction costs and the rebalancing frequency when making decisions on hedging. Bid-offer spreads, cost per trade and the rebalancing frequency are therefore relevant considerations. The volatility of the underlying is not something the trader would consider when taking decisions to delta hedge (unless as part of an active bet on future volatility) and therefore Choice 'c' is irrelevant to the trader's decision, and is the correct answer.