Answer:
C. It is negative
Step-by-step explanation:
As we know that mass of the bike is given as
m = 40 kg
now we know by Newton's law of motion

here we know that
m = mass of the bike
a = acceleration of the bike
so here we will have

now if the acceleration of the bike is in negative direction
then we will get a negative force on it as per above formula
so correct answer will be
C. It is negative