Charging by occurs when electrons are transferred from one object to another by direct contact
a. conduction
b. induction
c. reduction
d. friction

Charging by Conduction occurs when electrons are transferred from one object to another by direct contact.

Explanation:

Charging by Conduction happens when a charged object and a neutral object comes in contact. This is why it is also called charging by contact.

How it happens?

We know that like charges repel each other. Let us consider a negatively charged ball. It must have excess electrons and these electrons are as far from each other as they can get. When this negatively charged get in contact with a neutral ball. The electrons rush to the neutral ball to get away from the electrons on the negatively charged ball. In this act of getting away of electrons from each other, the neutral ball gets charged too.

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.