At the bottom-is the correct one.

Yes, a physical quantity can have magnitude and direction but still be a scalar if it doesn't obey the vector addition. An example is Electric Current which has magnitude and a fixed direction, but it does not follow vector laws of addition.

You can design such dialog boxes using the following website.
https://carbon.now.sh

Aksionov is the protagonist of the story "god sees the truth but waits" written by Leo Tolstoy. He is a young merchant. He is a handsome, fair-haired, curly-headed fellow, full of fun and very fond of singing. He used to drink much before marriage but later on, he changed himself and became a good man. He had virtuous qualities such as faith, forgiveness, freedom, and acceptance. His comfortable life is disrupted when he is framed for a murder he didn't commit and was sent to a...

Log_2aa=x    then, a=(2a)^x  ......(1)

Log_3a2a=y    then,2a=(3a)^y ......(2)

Log_4a 3a=z  then, 3a=(4a)^z ......(3)

So, 

a=(2a)^x  [from (1)]

Or, a=(3a)^xy    [from(2)]

Or, a=(4a)^xyz     [from(3)]

Multiplying both sides by 4a,

4a.a=4a.(4a)^xyz  

Or,(2a)² =(4a)^{xyz + 1} 

Or,(3a)^2y =(4a)^xyz+1 

Or,(4a)^2yz =(4a)^xyz+1 

Or, 2yz = xyz+1 .proved.

At dawn and dusk, large amount of blue and violet light(shorter wavelength) has been scattered so, the light that is recieved by an observer is mostly of a longer wavelength and therefore appears to be red.