Determine whether the underlined portion of the sentence below is correct or whether it needs to be revised.
For homes in typically colder geographic regions, it is particularly important to have effective and efficient heating systems.
The problem with this sentence is that it makes sense conversationally but not in written English. You cannot just say “colder geographic regions” when there is no object of comparison. Colder compared to what? An area can easily be identified as cold without a prior standard (such as the southern regions or areas near the equator) but not “colder.” Also, it is wrong to refer to people as the subject of this sentence because the second clause states that “it is particularly important to have...heating system.” People cannot have heating systems usually. Therefore, choice C, which uses a descriptive rather than comparative term, is the best choice.