Noun form of 'happy'.

**The reasoning** A **noun** is a word that names a thing, person, place, or *feeling*. When we convert the adjective "happy" (which describes how someone feels) into a noun, we add the suffix **"-ness"** to create **"happiness"** — the *state* or *condition* of being happy. Think of it this way: "She is happy" (adjective describing her) → "Her happiness is obvious" (noun — the thing we're talking about). Happiness is something you can possess, lose, or share. That's your clue it's a noun. **Why the wrong options tempt you** - **A) Happily** — This is an *adverb* (tells *how* something is done: "She laughed happily"). The "-ly" ending is your warning sign. - **C) Happier** — This is the *comparative* form of the adjective (comparing two things: "She's happier than him"). - **D) Happen** — Totally different word! It's a *verb* meaning "to occur." Sounds similar but unrelated. **Quick takeaway** To form nouns from adjectives describing feelings or states, look for **"-ness"**: sad → sadness, kind → kindness, weak → weakness.