Questions

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol

In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants parthenogenesis is a component process of apomixis.Apogamy is a type of reproduction, occurring in some ferns, in which the sporophytedevelops from the gametophyte without fusion of gametes.Adventitious embryony also called sporophytic budding, is a type of apomixis in which an embryo develops directly from nucellus or integument tissue.So, all three are correct.

Veins carries Blood back from the body parts to the Heart.

We know that The circulatory system of our body is a loop. The Heart is the pump, the arteries and their smaller branches (arterioles) carry oxygen rich blood all through your body and the veins and their smaller branches (venules) carry oxygen depleted blood and waste products back.

The nervous system of the human brain consists of the central nervous system which has brain and the spinal cord and the peripheral nervous system which has perpheral, cranary, spinal nerves.