Question

An apocarpous flower is found in
A. Caesalpinia
B. Ranunculus
C. Brassica
D. Datura

Answer 1

Gynoecium or pistil is a whorl of floral appendages or carpels. The gynoecium represents the female reproductive organ of the plant and consists of three distinct parts (a) ovary - it is the basal swollen part of the carpel or gynoecium which bears one or several ovules, (b) stigma - it is the receptive spot that lodges the pollen grains, and (c) style - it is a connection between stigma and ovary.

Complete answer:
The gynoecium is the collective term for the innermost or central whorl of floral appendages(i.e., carpel/ carpels). A unit of gynoecium is called a pistil.
According to the cohesion of carpels:
a. Apocarpous: The gynoecium comprises two or more carpels that are free; e.g. Ranunculus.
b. Syncarpous: gynoecium composed of two or more carpels which are fused; e.g. Hibiscus.
So, the correct answer is option B, i.e.,Ranunculus

Additional information :
Other terms related to gynoecium are
-Number of carpels
Monocarpellary: Gynoecium comprises a single carpel ; e.g. Leguminosae.
Bicarpellary: Comprised of two carpels. E.g. Acanthaceae.
Tricarpellary: Comprised of three carpels. E.g. Liliaceae
-Position of the ovary :
Superior: ovary is borne above the point of attachment of perianth and stamens on the thalamus. E.g. Citrus.
Semi inferior: The condition of the ovary is intermediate between superior and inferior; e.g. Rose
Inferior: ovary is borne below the point of attachment of perianth and stamens. The thalamus covers the ovary and fuses with it. E.g. Cucurbita

Note:
The other terms related to gynoecium according to the number of locules are unilocular, bilocular, trilocular, tetralocular, pentalocular, multilocular, according to placentation type are marginal, axile, parietal, free central, basal and superficial, according to style terminal, lateral, gynobastic and stylopodium and according to stigma are capitate, discoid, plumose, dumb-shell shaped, bifid, linear and stick.