What is usually the biggest problem involved in trying to re$-$estimate a project?

Question $6$Select one:

a$.$

The re$-$estimate is highly likely to worsen the project than improve it$.$

b$.$

The re$-$estimate could reflect an unrealistic improvement, which may place unfair demands on a team and probably lead to greater problems down the line.

c$.$

An estimate, once made, should never change.

d$.$

Re$-$estimating very often results in retrenchments.