This camera, is small and, very convenient and, is light. [Syntax]

The correct answer is "かるい". This is an い-adjective meaning "light." In a sentence listing multiple adjectives describing something, the final adjective in the list typically appears in its plain form (or polite form if it's the sentence ending). Here, "かるい" is the last descriptor before the polite sentence-ending "です", completing the description of the camera.

正解は「かるい」です。「軽い」というい形容詞（いけいようし）です。「～て、～て、～です」というように、いくつかの形容詞で物を説明（せつめい）する文（ぶん）の最後（さいご）に来る言葉（ことば）です。「とても」は「便利（べんり）で」と「軽い」の両方（りょうほう）にかかります。