To solve this problem, we need to identify which plant has a half inferior ovary. Let's analyze each option:$\newline \bullet$Mustard: Mustard belongs to the family Brassicaceae, which typically has a superior ovary.$\newline \bullet$Sunflower: Sunflower belongs to the family Asteraceae, which also typically has a superior ovary.$\newline \bullet$Plum: Plum belongs to the family Rosaceae, which is known for having a half inferior ovary. This is characteristic of the subfamily Prunoideae.$\newline \bullet$Brinjal: Brinjal, or eggplant, belongs to the family Solanaceae, which typically has a superior ovary.$\newline$Based on this analysis, the correct answer is Option 3: Plum, which has a half inferior ovary.