Select the most appropriate option to fill in the blank.

My teacher is the ______ of all.

kindest

The most appropriate option to fill in the blank is kindest.

The sentence is about the speaker's teacher, who is described as being very kind. The superlative form of the adjective "kind" is "kindest", which is the most appropriate word to use in this context because it expresses the speaker's belief that their teacher is the kindest person they know.

The other options are not as appropriate.

• Kind is the positive form of the adjective "kind", which is not as strong as the superlative form.
• Kinder is the comparative form of the adjective "kind", which is used to compare two people or things. In this context, the speaker is not comparing their teacher to other people, they are simply stating that their teacher is the kindest person they know.
• Kindly is an adverb that means in a kind way. It is not appropriate to use in this context because the sentence is about the speaker's teacher, not the way that the teacher acts.