In mammals, blood returning from the head will pass through the just before entering the right atrium.

Jungular veins

Explanation:

The jungular veins situated in the neck collects deoxygenated blood from the capillaries of the head and neck and channels it to the right atrium.

Thus, jungular vein is the answer

X=92.49 m

Explanation:

Given that

u= 21 m/s

h= 97 m

Time taken to cover vertical distance h

h= 1/2 g t²

By putting the values

97 = 1/2 x 10 x  t²          ( g = 10 m/s²)

t= 4.4 s

The horizontal distance

X= u .t

X= 21 x 4.4

X=92.49 m