Select the verb form that most appropriately completes the following…

The correct answer is Option (2) → has messaged

Present perfect with "since":

• A period that runs from a past point up to now takes the present perfect (has/have + past participle).
• Finished actions that are counted (once, twice, three times) take the simple form, not the continuous.
• This sentence:
  • "Since the time she moved to Athens" runs up to the present, so the present perfect is needed.
  • "Once or twice" counts finished messages, so the simple form has messaged fits.
• Complete sentence: My sister has messaged me once or twice since the time she moved to Athens.

Why the Other Options are Incorrect?

Option 1: was messaging — Incorrect. The past continuous shows an action in progress at a past moment. It cannot link a past point to the present with "since".
Example: She was messaging her friend when the bus arrived.

Option 3: will message — Incorrect. Will message refers to the future. The sentence counts messages already sent in the period "since the time she moved", which runs up to now.
Example: I will message you when I reach home.

Option 4: had been messaging — Incorrect. The past perfect continuous needs a later past event as a reference point. Here the period runs up to the present.
Example: She had been messaging him for weeks before they finally met.

Contrast: "since" with a period up to now takes the present perfect (has messaged). The past perfect continuous (had been messaging) needs a later past event as its reference point.

Note: In the original NTA paper, Option 3 read "has been messaging". NTA accepted this option as a correct answer as well. To leave only one correct answer and avoid confusion for students, it has been changed here to "will message".

Advice for the exam: In the real exam, mark the answer that is grammatically or factually correct. If NTA’s provisional answer key marks a different option, challenge it during the answer-key challenge window and give the reason in one or two lines.