attack, strike
攻撃（こうげき）、衝撃（しょうげき）、射撃（しゃげき）
attack, shock, shooting
On-reading (ゲキ) is used in compounds; kun-reading (う(つ)) is used standalone or with okurigana. Appears in many compounds — memorize the key ones rather than the kanji in isolation. This kanji forms verbs/adjectives with okurigana. Practice both the word form and compound forms.
From the JLP Quiz question bank — the word in the form it is actually tested in.
この強烈な映像は、見た者に衝撃を与え___。
Answer: ずにはおかない
警察は目撃者の証言から犯人の行動を（ ）した。
Answer: 推測
