Answer:
C. -1m/s² east
Explanation:
starting velocity u= 8m/s
final velocity  v=7m/s
time t=1second
we know,
average acceleration=(v-u)/t
                  ={ (7-8)/1 } m/s²
                  =(-1/1 ) m/s²
                  =-1 m/s²
the result is negative because his  final velocity is less than  starting velocity. That means there will be deceleration instead of acceleration.