この漢字は形が複雑で、覚え___です。
Q. Which suffix means 'hard to (memorize)'?
Translation
This kanji has a complex shape and is hard to memorize.
Explanation
Masu-stem + にくい means 'difficult to do': 覚えにくい. やすい is the opposite ('easy to'), and すぎる would mean 'too much'.