If Task C has 0 days of free float and 0 days of total float, what does this mean to the project

A) The project does not have adequate lead and lag times built in.
B) The task is on the critical path.
C) The duration of the task should be compressed.
D) The dates for the task are not accurate.

通常在路基水温状况不良或有冻胀的土基上，都应在基层之下加设垫层。