Answer:
B. In addition
Step-by-step explanation:
"Furthermore" is a conjunctive adverb. In the sentence above, it means the speaker would like to add more information that will support the prior sentence about cell phones being useful as everyday objects. So this makes "in addition" as the best transition among the given choices. Another transition possible would be "besides."
Remember that once conjunctive adverbs are used at the beginning of sentences, they are followed by a "comma." In this sense, it tries to link the two sentences above or it may also be used to link two independent clauses.