Blood circulation that starts in capillaries and ends in capillaries is called:

$A$ portal system is one in which

Given below are two statements regarding the circulation of blood in fishes.
Statement $I$: The heart of a fish contains only deoxygenated blood.
Statement $II$: Fishes show single circulation,and blood passes through the heart only once during each cycle.
In light of the above statements,choose the correct answer from the options given below.

The course of blood flow in pulmonary circulation is . . . . . . . . . . . . .

Mammals are said to have a "double circulatory system". This means

Which of the following represents the correct pathway of the circulatory system?