Hydrogen has four emission lines in the visible light range : violet, blue, green, and red. match the color of the emission line to its electron transition.

a. n =  4     →   n =  2 
b. n =  3     →   n =  2
c. n =  6    →   n =  2
d. n =  5    →   n =  2 

C.    n = 6   →   n = 2     Violet

D.    n = 5   →   n = 2     Blue

A.    n = 4   →   n = 2     Green

B.    n = 3   →   n = 2     Red

Explanation:

The transitions involved are all to energy level n=2  from higher energy levels. The energy of the emission line correspondingly will reflect a higher energy the greater n is and the color of the emission spectra line will likewise correspond to higher energy. Since the energy of the colors given  follow the sequence:

Remember that the the energy and the frequency of the visible colors is greatest for violet and lowest for red. That is why we refer  to ultraviolet light being highly energetic ( sunburn) and infrared gogles which are used for low energy night vision ( the ultra and infra mean beyond visible spectrum)

away from the curb

explanation:

the wheels would then hit the curb if it started to rolling, decreasing the chance of an accident.

it is the most commonly accepted one