Option 1 -> "ingenuous" means naive, innocent, or unsophisticated - the opposite of shrewd/clever.
Option 2 -> "avid" means enthusiastic or eager - relates to intensity of interest, not cleverness.
Option 3 -> "infamous" means having a bad reputation - relates to reputation, not perception.
Option 4 -> "morose" means gloomy or sullen - relates to mood, not intelligence.
Hence, Option 1: ingenuous -> "Astute" means shrewd and perceptive, while "ingenuous" means lacking sophistication or worldly experience, making them direct antonyms -> correct