The word <em>wishing </em>is used as a participle in this case. Although gerunds and participles look the same, they are used in different senses - gerunds generally denote nouns, whereas participles have more of an adverbial meaning.
<span>In order to vary the sentence structure, the sentence I would insert in the blank is C. Have you noticed how hard she works? The reason for this is because inserting an interrogative sentence that has a completely different structure and word order than the other two sentences works great in order to introduce some versatility into a paragraph consisting of a couple of sentences. Here, the only sentence that differs is C. which is why you should choose it. Starting three sentences in a row with the same word can be a bit dull and repetitive. </span>
It's A as to the avoiding double negation which is not possible in English.
