Correct option is D

Given:

Karan's marks in different subjects:
Physics: 92% of 100 = 92
Chemistry: 90% of 100 = 90
Maths: 90% of 100 = 90
English: 93% of 100 = 93 
Formula Used:
​$$\text{Percentage} = \left( \frac{\text{Obtained Marks}}{\text{Total Marks}} \right) \times 100$$​​
Solution:
Total marks obtained by Karan = 92 + 90 + 90 + 93 = 365 
Total Maximum Marks = 400
Overall percentage = $$\left( \frac{365}{400} \right) \times 100 = 91.25\%$$​​

Correct option is D

Given:
Highest scores in Physics:
Radhika: 90% of 100 = 90
Karan: 92% of 100 = 92
Neeraj: 86% of 100 = 86
Sujata: 77% of 100 = 77
Formula Used:
​$$\text{Average Marks} = \frac{\text{Sum of all marks}}{\text{Number of subjects}}$$ 
Solution:
​$$\text{Average Marks} = \frac{90 + 92 + 86 + 77}{4} = 86.25$$​​

Correct option is B

Given:
Marks obtained by Neeraj:
Physics: 86% of 100 = 86
Chemistry: 82% of 100 = 82
Maths: 75% of 100 = 75
English: 77% of 100 = 77
Solution:
Best three subjects: Physics (86), Chemistry (82), Maths (77)
Total marks in best three subjects = 86 + 82 + 77 = 245
Percentage in best three subjects = $$\left( \frac{245}{300} \right) \times 100 \approx 81.66$$%

Correct option is A

Solution:
Radhika: 90 (Physics) + 85 (Chemistry) + 95 (Maths) + 98 (English) = 368
Karan: 92 (Physics) + 90 (Chemistry) + 90 (Maths) + 93 (English) = 365
Neeraj: 86 (Physics) + 82 (Chemistry) + 75 (Maths) + 77 (English) = 320
Priyanka: 63 (Physics) + 48 (Chemistry) + 55 (Maths) + 75 (English) = 241
Sujata: 77 (Physics) + 62 (Chemistry) + 80 (Maths) + 85 (English) = 304
Preeti: 50 (Physics) + 52 (Chemistry) + 40 (Maths) + 59 (English) = 201
The highest aggregate marks are achieved by Radhika, with a total of 368 marks.

Correct option is D

Given:
Radhika: 90
Karan: 92
Neeraj: 86
Priyanka: 63
Sujata: 77
Preeti: 50
Solution:
Radhika : Karan =$$\frac{90}{92} = 0.978$$​​

Neeraj: Karan = $$\frac{86}{92} = 0.9348$$ 

Sujata : Neeraj = $$\frac{77}{86} = 0.8953$$​​

Priyanka : Sujata:  $$\frac{63}{77} = 0.818$$​​
The pair with the smallest ratio between their Physics marks is Priyanka and Sujata, with a ratio of 0.818.