This question refers to a specific legal section and the conditions under which enforcement powers are activated, typically in the context of environmental or public nuisance law. The correct answer is Non-compliance with an Absolute Order.
Enforcement powers are generally invoked when a legally binding and definitive order, such as an Absolute Order, is not followed. This breach of a formal directive is the logical trigger for coercive action under Section 36(5).
Issuing an EPO (A) is an initial, often temporary, order; it doesn't trigger enforcement under this section.
Filing a representation (C) is an objection or appeal, which might delay or challenge an order, but does not trigger enforcement.
A whistle-blower's complaint (D) initiates the process, leading to an investigation and potentially an order, but it's the non-compliance with the order that triggers enforcement.