Answer:
brightest
Step-by-step explanation:
The superlative of the adjective 'bright' is 'brightest, placed after the article 'the': the brighest. 'Brighter' is the comparative form which is followed by 'than': brighter than. Short adjectives form their comparative by adding 'er' + 'than'.; and their superlative: the + adjective + est. For long adjectives, we form the superlative with the + 'most' + adjective. And the comparative: more + adjective + than.