A useful alternate way to approach this kind of odd-word-out question is to look at word roots and origins rather than just definitions, since words that cluster together in meaning often share a common root.
Malicious, spiteful, and malevolent all describe a wish or intent to cause harm to someone else, while inhibitive is about holding something back or restraining a process, a completely different idea rooted in restriction rather than harmful intent.
Therefore, the correct answer is Inhibitive.