The variation of the decay rate of two radioactive samples A and B with time is shown in the figure.

              

Which of the following statements are true?
 

a. Decay constant of A is greater than that of B, hence A always decays faster than B
b. Decay constant of B is greater than that of A but its decay rate is always smaller than that of A
c. Decay constant of A is greater than that of B but it does not always decay faster than B
d. Decay constant of B is smaller than that of A but still its decay rate becomes equal to that of A at a later instant

1. (a, b)

2. (a, c)

3. (b, d)

4. (c, d)