Answer:
1. The scoring scheme which has 5 question choices
Probability of giving one correct answer

=20%
2. The scoring scheme which has 4 question choices
Probability of giving one correct answer

=25%
3. The scoring scheme which has 3 question choices
Probability of giving one correct answer

=33.34%
The Scoring scheme which has 3 question choices is most favorable to test taker.