Answer:
A.. Number of elements in the sample space is 10.
B.. Given that event B is card drawn is blue. 
Step-by-step explanation:
Special deck has3 blue and 7 orange cards. The blue cards are numbered 1, 2 and 3. The orange cards are numbered 1, 2, 3, 4, 5, 6 and 7.
We draw one card randomly from the deck, the sample space is 
S={b1, b2, b3, o1, o2, o3, o4, o4, o6, o7}
Where, 
'b' represents blue card
And 'o' represents orange cards.
Number of elements in the sample space is 10.
Given that event B is card drawn is blue. 
B={b1, b2, b3}.