Why is it important to understand alternating current when learning about networks?

Question $22$ options:

a$)$

The AC signal changes over time, which gives standards groups more options for how to encode data using electricity

b$)$

The AC signal does not change over time, which gives standards groups more options for how to encode data using electricity

c$)$

The DC signal changes over time, so standards groups cannot easily use it to describe how data can be encoded for electricity

d$)$

The DC signal does not accurately reflect how data is transmitted, so AC is the preferable method for developing encoding schemes