Question

The four whorls of a flower are arranged on the ______
A. Peduncle
B. Thalamus
C. Petiole
D. Pedicel

Answer 1

Reproduction in the flowering plants starts with the process of pollination, the transfer of pollen grains from anther to stigma on the same flower or else to the stigma of another flower on the same plant is known as self pollination or from the anther on one plant to the stigma of another plant is known as cross-pollination.

Complete answer:
Option A Peduncle: It is an elongated stalk of tissue. A stalk is the one which bears a flower or flower cluster or a fructification.
Option A is not correct.
Option B Thalamus: The flower has four whorls that is Androecium (stamen), Gynoecium (Pistil), Corolla (petals), Calyx (Sepals) are collectively arranged on the thalamus /receptacle.
So, option B is correct.
Option C Petiole: The petiole is a stalk that attaches a leaf to the plant stem. Most people call it a stem, which is not right. The stem is the part of the plant it provides as the main source of support and produces nodes and roots, and that's not what we observe in petioles.
So, option C is not correct.
Option D Pedicel: A small stalk which bears an individual flower in an inflorescence. The pedicel, a stalk, connects to the base of the flower or fruit that attaches the organ to the plant body.
So, option D is not correct.

Hence, Option B is the correct answer.

Note:
The Thalamus is located near the stalk of the flower. It is a modified stem which possesses nodes and internodes. The thalamus supplies nutrients to the flower. The receptacle or torus is the thickened part of the stem from which the part of flower organs grow. The stamens and pistils are involved in the production of seed.