Which among the following is not a true fruit?

In botanical terms, a 'true fruit' is a ripened ovary formed after fertilization. A 'false fruit' or 'accessory fruit' is one where the fleshy part is derived from tissues other than the ovary, such as the thalamus or receptacle [t1][t9]. The apple is a classic example of a false fruit (specifically a pome); while the core contains the seeds derived from the ovary, the edible fleshy part develops from the floral receptacle [t2][t8][t9]. In contrast, grapes are true fruits classified as berries [t5][t7]. Plums and dates are also true fruits classified as drupes (stone fruits), where the fleshy part develops directly from the ovary wall [t2][t5][t8]. Therefore, among the given options, the apple is the only one not considered a true fruit in strict botanical classification [t9].

Sources

1. [1] https://www.fs.usda.gov/wildflowers/ethnobotany/food/fruits.shtml
2. [2] https://en.wikipedia.org/wiki/Berry_(botany)