Given Information:
A candidate is required to answer 6 out of 12 questions divided into two groups containing 6 questions in each group.
He is not permitted to attempt not more than four from any group.

To Find: The number of choices

Solution:
We can solve this problem by using the combination formula.

Number of ways of selecting r objects from n distinct objects = nCr = n! / (r! * (n-r)!)

Let's find the number of ways of selecting 6 questions under the given conditions.

Group 1:
Number of ways of selecting 4 questions out of 6 questions = 6C4 = 6! / (4! * 2!) = 15
Number of ways of selecting 5 questions out of 6 questions = 6C5 = 6! / (5! * 1!) = 6
Number of ways of selecting 6 questions out of 6 questions = 1

Total number of ways of selecting 6 questions from group 1 = 15 + 6 + 1 = 22

Group 2:
Number of ways of selecting 4 questions out of 6 questions = 6C4 = 6! / (4! * 2!) = 15
Number of ways of selecting 5 questions out of 6 questions = 6C5 = 6! / (5! * 1!) = 6
Number of ways of selecting 6 questions out of 6 questions = 1

Total number of ways of selecting 6 questions from group 2 = 15 + 6 + 1 = 22

Total number of ways of selecting 6 questions = (Number of ways of selecting 6 questions from group 1) * (Number of ways of selecting 0, 1, or 2 questions from group 2)
+ (Number of ways of selecting 0, 1, or 2 questions from group 1) * (Number of ways of selecting 6 questions from group 2)
+ (Number of ways of selecting 5 questions from group 1) * (Number of ways of selecting 1 question from group 2)
+ (Number of ways of selecting 1 question from group 1) * (Number of ways of selecting 5 questions from group 2)
+ (Number of ways of selecting 4 questions from group 1) * (Number of ways of selecting 2 questions from group 2)
+ (Number of ways of selecting 2 questions from group 1) * (Number of ways of selecting 4 questions from group 2)

Total number of ways of selecting 6 questions = (22 * 231) + (231 * 22) + (6 * 6) + (6 * 6) + (15 * 15) + (15 * 15)
= 850

Therefore, the number of choices is 850.

Answer: Option B. 850

A. B. = 6 questions. he should answer
4. 2. =6( condition not to attend more 4 in each )
2. 4. =6
3. 3. =6
so 6C4×6C2=225
6C2×6C4=225
6C3×6C3=400

225+225+400= 850
so option (b) is correct