Throwing a coin

This task is about chance when throwing a coin. 
 
David throws a fair coin six times. Each throw is just as likely to come up as Heads (H) or Tails (T).

Question

Which of the following sequences is the most likely to occur?  (circle one answer below)

    • H  T  T  H  T  H

    • T  H  T  T  H  T

    • H  T  H  H  H  H

    • T  T  T  T  T  T

    • They are all equally likely

Explain the reasons for your choice