An object has an acceleration of 1.2 cm/s^2. At t = 4s, its velocity is -3.4 cm/s. Determine the object's velocities at t = 1s and t = 6s.
A. Positive at t = 1s, Negative at t = 6s
B. Negative at t = 1s, Positive at t = 6s
C. Positive at both t = 1s and t = 6s
D. Negative at both t = 1s and t = 6s