Answer:
C. representative elements.
Explanation:
Families 1 - 2 and 13 - 18 are called representative elements or often times, main group elements.
- Elements on the periodic table belongs to four blocks which are s, p, d and f blocks.
- Those in the s and p-blocks are the main group elements also called representative elements.
- Their outer-shell are not completely filled with electrons but their inner shell is completely filled.
You have to do a report :

So
the truck efficiency is 38%.
B is the.answer for this problem
Answer: it would be cation, 2+
Explanation: electrons are negatively charged by 1. So if you get rid of 2 electrons it would be positive and cation is used to represent positive ions.
The reactant is what you begin with.
The product is what you end up with (so the answer is B)