Here are some examples:
* Sensible: having or showing good sense or reason.
* Insensible: unconscious or unaware; not aware of or responsive to one's surroundings.
The other options you listed are prefixes as well, but they don't apply to "sensible":
* im-: often used before words beginning with "p" or "b" (e.g., impossible, improbable)
* ir-: often used before words beginning with "r" (e.g., irregular, irresponsible)
* your: a possessive pronoun, not a prefix
* il-: used before words beginning with "l" (e.g., illegal, illiterate)
* dis-: used to indicate negation or reversal (e.g., disagree, dishonest)