Given data:
* The initial velocity of the arrow is 90 m/s.
* The time taken by the arrow is 6 seconds.
* The acceleration of the arrow while moving in the upward direction is,

Solution:
By the kinematics equation, the final velocity of the arrow in terms of the initial velocity, acceleration, and time is,

where v is the final velocity, u is the initial velocity, g is the acceleration due to gravity and t is the time taken,
Substituting the known values,

Thus, the final velocity of the arrow is 31.2 m/s.
Hence, option A is the correct answer.