Which of the following is an element in the sample space for forest tossing a coin and then rolling a number cube a- t, h b- 4,6 c- h,8 d-t,4

The first part has to be either Heads or Tails
The second part can be any number on a normal dice which is 1 through 6.
A is wrong because it has nothing about the dice.
B is wrong because it has nothing about the coin toss.
C is wrong because 8 is not a number on a normal dice.

Therefore, D is your answer since it has a result from a coin toss and then a result from rolling a dice.