Step 1: Break the word into parts.
The word is a, cco, mmo, dation. The tricky bits are the double letters.
Step 2: Recall the double-letter rule.
The correct spelling has a double c and a double m together.
Step 3: Test option 1.
Accomodation has only one m, so it is wrong.
Step 4: Test options 2 and 4.
Accommadation puts an a where an o belongs, and Acommodation drops a c. Both wrong.
Step 5: Test option 3.
Accommodation has the double c, the double m, and the right vowels.
Step 6: State the answer.
The correct spelling is Accommodation. \[ \boxed{\text{Accommodation}} \]