The correct answer is the last one.
The addition of the suffix -ion changes the root word from a verb to a noun.
Without the suffix, the word is "construct." This word is a verb meaning "to build." By adding the suffix -ion, the word "construct" becomes the word "construction." The word "construction" is a noun meaning "a building."
Therefore, the correct answer is the last one. The suffix turns a verb into a noun.