What does "carry off" mean?

[micha]

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #127 "Idioms with the phrasal verb carry", question 1

An eagle, if pressed for food, might ......... a small baby that had been left in the open unprotected, but such an opportunity must occur very rarely.

(a) carry off
(b) carry through
(c) carry on with
(d) carry out

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #127 "Idioms with the phrasal verb carry", answer 1

An eagle, if pressed for food, might carry off a small baby that had been left in the open unprotected, but such an opportunity must occur very rarely.

Correct answer: (a) carry off

Your answer was: incorrect
An eagle, if pressed for food, might carry on with a small baby that had been left in the open unprotected, but such an opportunity must occur very rarely.
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what does carry off mean?

micha

[Mister Micawber]

.
Carry off = carry away. Here, the eagle might carry a baby off the ground and away to its feeding perch.
.
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Native English teacher at Mister Micawber's

[Baubau]

Hello,
Could someone please explain why is "had been left" used here (and not "has been left")?
Thanks in advance.