$1\mathrm{.}3$ In a network, an activity can be shown in one of three conditions. Identify the statement that does not correctly

describe one of the three possible conditions.

a$)$ The activity may have a successor but no predecessor

b$)$ The activity may have a predecessor but no successor

c$)$ The activity may have a predecessor and a successor

d$)$ The activity may have neither a predecessor nor a successor