Among your options, there is only one clause, and that would be A. "she got soaked walking." When it comes to clauses, they need to have a subject (she in A), and a verb (got soaked in A). The other options don't have both the subject and the verb and thus cannot be considered clauses. There is however another clause in this sentence (because her umbrella was in her gym locker), but it is not one of your options.
