Explanation:

Let’s break it down line by line:

- The sentence says Elephant Island’s name is attributed to (1) ______ its elephant head-like appearance and the sighting of elephant seals...

- The meaning here is, the name comes from two reasons: (a) its appearance, and (b) the elephant seals.

- Let's look at the options:

1. either — “either its elephant head-like appearance and the sighting...”

? Doesn’t work. "Either" would need an “or,” not “and.”

2. also — “also its elephant head-like appearance and the sighting...”

? Feels awkward. Also doesn’t fit smoothly here, especially before listing two things at once.

3. both — “both its elephant head-like appearance and the sighting...”

Perfect. "Both...and..." sets up two related causes. This matches the structure and sense.

4. neither — “neither its elephant head-like appearance and the sighting...”

? Would only work in a negative sentence, but this isn’t one.

The correct answer is:

Option 3: both

You nailed it—“both” fits naturally, clarifies there are two sources for the island’s name, and just makes the whole thing flow better.