Problem:
The probability that there are 53 Sundays in a randomly chosen leap year is:

a) 1/7
b) 1/14
c) 1/28
d) 2/7

The correct answer is option 'D'. Let's explain why it is the correct answer.

Leap Year:
A leap year is a year that is exactly divisible by 4, except for years that are divisible by 100. However, years that are divisible by 400 are also leap years. This means that every 4 years, there is an extra day, February 29th, in the calendar.

Number of Days in a Leap Year:
In a leap year, there are 366 days instead of the usual 365 days. This is because of the extra day, February 29th.

Number of Weeks in a Leap Year:
Since there are 7 days in a week, the total number of weeks in a leap year is given by:
Total number of weeks = Number of days / Number of days in a week
= 366 days / 7 days per week
= 52 weeks and 2 days

Number of Sundays in a Leap Year:
To find the probability of having 53 Sundays in a leap year, we need to determine the number of Sundays that can occur in a leap year.

In a leap year, the first day of the year can be any day of the week. Let's consider each possibility:

1) If the first day of the year is a Sunday, then there will be 53 Sundays in the year.
2) If the first day of the year is a Monday, then there will be 53 Sundays in the year.
3) If the first day of the year is a Tuesday, then there will be 52 Sundays in the year.
4) If the first day of the year is a Wednesday, then there will be 52 Sundays in the year.
5) If the first day of the year is a Thursday, then there will be 52 Sundays in the year.
6) If the first day of the year is a Friday, then there will be 52 Sundays in the year.
7) If the first day of the year is a Saturday, then there will be 52 Sundays in the year.

In options a), b), and c), the probability given is less than 1/7, which means it is incorrect. The only option left is option d), which is 2/7. This is the correct answer.

Conclusion:
The probability that there are 53 Sundays in a randomly chosen leap year is 2/7, which is the correct answer (option 'D').