What are the sentences to choose from ?
<span>Without placing too implicit faith in the account above given, it must be agreed, that if a worthy pretext for so dangerous an experiment as setting houses on fire (especially in these days) could be assigned in favor of any culinary object, that pretext and excuse might be found in roast pig.</span>
Iambic pentameter is fives sets of iambs, or one unstressed followed by one stressed.
The only choice that matches that description is option A.
The others all start with a stressed syllable, so they can not be iambs.
Hope this helps =)