The objective is to find the antonym for the underlined word "showed" within the sentence: "The thief showed his disbelief when informed that his partner had been arrested."
"Showed" signifies the act of displaying or revealing. Consequently, we seek a word that denotes hiding or not revealing. Let's examine the provided choices:
Following this evaluation, "concealed" is identified as the correct opposite of "showed." Therefore, the answer is concealed.