Question

Which of the following option is correct?

$\left(1\right)$	Osteichthyes	$4$ pairs of gills covered by an operculum
$\left(2\right)$	Chondrichthyes	$6-15$ pairs of gill slits
$\left(3\right)$	Arthropoda	Metamerism and excretion by nephridia
$\left(4\right)$	Platyhelminthes	Bilateral symmetry & coelomate e.g., Taenia and Fasciola

• A. A
• B. B
• C. C
• D. D

Answer 1

The correct option is A A

• Osteichthyes includes both marine and freshwater fishes with a bony endoskeleton.
• Their body is streamlined. The mouth is mostly terminal. They have 4 pairs of gills which are covered by an operculum on each side. The heart is two-chambered (one auricle and one ventricle). For example, Exocoetus (Flying fish), Hippocampus (Sea horse); Freshwater – Labeo (Rohu), Catla (Katla), Clarias (Magur);
• Hence Osteichthyes have 4 pairs of gills covered by an operculum.
• So, the correct answer is 'Option A'.