(D) Both I and II are true and II is the correct explanation of I.
Statement I is true as technology in telecommunications, computers, and Internet has been changing rapidly. Statement II correctly explains this by giving the example of e-mail and voice-mail, showing how internet technology drives rapid change.
Source: Factors that have enabled Globalisation — Technology, Chapter 4
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Statement I is directly from the textbook: "In recent times, technology in the areas of telecommunications, computers, Internet has been changing rapidly." Statement II is also from the same paragraph: "Internet also allows us to send instant electronic mail (e-mail) and talk (voice-mail) across the world at negligible costs." Since II gives a concrete example of why/how technology is changing rapidly, it directly explains Statement I — making option (D) correct, not just (C). Watch out: choose (C) only when both are true but II is unrelated to I.