Employment

Question: Mark has been continuously employed by Stone Ltd for 18 months. He is dismissed, with notice, by this employer for requesting paid holiday leave.
Which of the following statements is true?
a) The reason for dismissal is automatically unfair, so Mark can bring action for unfair dismissal regardless of his length of employment
b) Mark cannot bring an action for unfair dismissal since he has not been in continuous employment for more than 2 years
c) Mark can claim statutory redundancy pay
d) Mark can claim constructive dismissal
In the above question, why option b) is not correct and why the correct one is really correct. Is it because there is no time limit specified in case of unfair dismissal whereas there is a limit for redundancy pay