Shark's tooth

[RonPurewal]

Logically "each one(teeth)" refers to the teeth, but grammatically isn't it creating ambiguity? I mean grammatically can't each one refer to reserve, and, thus creating ambiguity?

two things:

1/
there's only one reserve, so "each one" can't apply here anyway.

2/
there is no such thing as "grammatical ambiguity". if something has one reasonable interpretation and one totally ridiculous/absurd/nonsense interpretation, then it's NOT "ambiguous".

[RonPurewal]

your understanding of "whenever" is correct.

"when" can be used for a single instance, and can ALSO be used with the same meaning as "whenever".
(the purpose of "whenever" is to emphasize the lack of restriction and/or the universal quality of something. in other words, the choice to use "whenever", instead of just "when", is totally stylistic -- not the kind of thing that's tested on this exam.)