If there are legal options to choose, the ability’s controller must choose them. They may not decline this stage of playing a Trigger.
§ 402.4.b Core Rules PDF (officieel)
§ 402 2. Make relevant choices
§ 402.4 If there are not enough options to make legal choices for a Triggered Ability that has been put on the chain, remove it from the Chain now. It ceases to be a Pending Item but never becomes a Finalized Chain Item.
