Select the most appropriate words to fill in the blanks in the given…

The correct answer is Option (2) → had already ended, had gathered

Past perfect tense with “by the time”:

• When two actions in the past are compared, the one that happened first takes the past perfect (had + past participle). The later one takes the simple past.
• “By the time + simple past” fixes a point in the past. Whatever was complete before that point takes the past perfect.
• This sentence:
  • Later action, the time marker: “By the time we arrived” (simple past).
  • Earlier actions: the concert ended and the crowd collected in the parking lot before that point.
  • So both blanks take the past perfect: had already ended and had gathered.

Complete sentence: By the time we arrived, the concert had already ended and the crowd had gathered in the parking lot.

Contrast: the past perfect (had ended, had gathered) shows actions complete before the past point “By the time we arrived”. The simple past or the past continuous would place them at that point or still going on.

Why the Other Options are Incorrect?

Option 1: has ended, was gathering — Incorrect. The present perfect "has ended" links the past to the present and cannot follow a past time clause like "By the time we arrived".
Example: The rain has ended, so we can go out now.

Option 3: ended, gather — Incorrect.

• "Gather" is in the present tense and does not agree with a sentence set in the past.
• "By the time" calls for the past perfect for the earlier actions, not the simple past "ended".
  Example: The birds gather on this tree every evening.

Option 4: was ending, gathered — Incorrect.

• The past continuous "was ending" shows the concert still going on, which does not fit "By the time".
• The simple past "gathered" does not show the crowd collecting before our arrival.
  Example: The match was ending when the lights went out.