Generally no costs are payable between the parties where an order is silent on costs (CPR, r. 44.10(1), which is technically not on the syllabus, but which is referred to in PD 23A, para 13.2, including the effect as set out in answer [C], which is on the syllabus). The exceptions to the rule in r. 44.10(1) (set out in r. 44.10(2) only arise in appeals, judicial review and interim injunctions, so do not arise on the facts.
The correct answer is: No costs are payable between the parties in respect of the interim application.