In Rubus idaeus/Raspberry the fruit is
A. Berry
B. Etaerio of berries
C. Etaerio of drupes
D. Etaerio of achenes

Hint: Raspberry is an aggregate fruit, which means that the fruit is developed from a flower possessing an apocarpous pistil. An apocarpous pistil is a pistil where multiple fruits develop on the same thalamus. Aggregate fruits have a common prefix “etaerio”, and raspberries are etaerio of drupes, as each bulb of the berry is a single drupe or drupelet.

Complete answer: When it comes to fruits, we can broadly classify them into simple, aggregate, and multiple fruits. From their name, we can ascertain that simple fruits are ones that grow from a single seed or a simple ovary. Whereas, aggregate fruits are multiple simple fruits that grow on a single flower that has multiple ovaries. And in the case of multiple fruits, there are a bunch of different flowers each forms a fruit, but mature into a single fused fruit. Examples are as follows:
a) Simple fruits - Mangos, Peaches, etc.
b) Aggregate fruits – Blackberry, Raspberry, etc.
c) Multiple fruits - Pineapple, Oranges, etc.
Not all aggregate fruits fuse to form a simple fruit. There are many types of aggregate fruits present and all have a common prefix of etaerio. The fruit of raspberry is the etaerio of berries.
Hence, the correct answer is option B.

Note: Raspberry is considered a drupe as it has distinct pericarp layers and a stony seed in the middle. A berry is a fleshy fruit without a stony seed (pit) and does not have distinct pericarp layers. An achene is not a flesh fruit, here, the seed is stony and fills the entire pericarp, examples are buckwheat, caraway, quinoa, etc.