If it was a Friday on 1 January 2016, what was the day of the week on 1 January 2017?

To find the day of the week on 1 January 2017, we need to determine how many days elapsed from 1 January 2016 to 1 January 2017.

---

First, check if 2016 is a leap year.

A year is a leap year if it is divisible by 4 (with the exception that years divisible by 100 must also be divisible by 400).

$2016 \div 4 = 504$

Since 2016 is divisible by 4 and not a century year, 2016 is a leap year.

Therefore, 2016 has 366 days.

---

The number of days from 1 January 2016 to 1 January 2017 is 366 days.

To find the day of the week, we calculate:

$366 \div 7 = 52$ remainder $2$

This means 366 days = 52 complete weeks + 2 extra days.

---

Starting from Friday (1 January 2016), adding 2 days:

Friday + 1 day = Saturday

Saturday + 1 day = Sunday

Therefore, 1 January 2017 was a Sunday.

The correct answer is Option 4: Sunday.