Answer: A) Angrier.
Explanation: Adjectives can compare two things or more than two things. To do that, we use comparative and superlative forms of adjectives. The comparative adjectives can be formed by adding "-er" at the end of the adjective (thinner, brighter, prettier, etc), or by writing the word "more" before the adjective (more beautiful, more boring, etc). The comparative form or the adjective "angry" is "angrier" so the correct answer is option A.