The answer is longitudinal waves
Explanation:
The given reaction equation is as follows.
+ ___ 
As there is release of one hydrogen which shows that mass number has increase by 1 on the product side.
Therefore, particle
must be added in order to balance the given reaction equation.
Hence, the complete reaction equation will be as follows.

A. build proteins
Explanation:
The endoplasmic reticulum can either be smooth or rough, and in general its function is to produce proteins for the rest of the cell to function. The rough endoplasmic reticulum has on it ribosomes, which are small, round organelles whose function it is to make those proteins
Answer:
Refering to Chemistry,
The Group names are:
Group 6A: Chalcogens
Group 7A: Halogens
Group 8A: Noble/Inert Gasses