The obstacles seem to be insurmountable, but no one should doubt what this fearless woman can accomplish.

Answer: Option B

Achieve : successfully bring about or reach (a desired objective or result) by effort, skill, or courage.
Insuperable : (of a difficulty or obstacle) impossible to overcome.
Tall : of great or more than average height, especially (with reference to an object) relative to width.
Trivial : of little value or importance.
Insurmountable : too great to be overcome.

Synonym of Insurmountable is Insuperable