Which of the Following Is a Portal System?
A)Heart $\rarr$ Artery $\rarr$

Which of the following is a portal system?

A) Heart $\rarr$ artery $\rarr$ vein $\rarr$ heart
B) Heart $\rarr$ artery $\rarr$ arteriole $\rarr$ capillary bed $\rarr$ arteriole $\rarr$ capillary bed $\rarr$ venule $\rarr$ vein $\rarr$ heart
C) Heart $\rarr$ artery $\rarr$ artery $\rarr$ arteriole $\rarr$ capillary bed $\rarr$ venule $\rarr$ vein $\rarr$ heart
D) Heart $\rarr$ artery $\rarr$ arteriole $\rarr$ capillary bed $\rarr$ venule $\rarr$ vein $\rarr$ vein $\rarr$ heart