Arun remembers that his brother’s wedding is certainly after the 15th but before the 19th of October. His mother remembers that the wedding is definitely after the 16th but before the 20th of October. If both are correct, on which date of October is the wedding?

To find the correct date, we must look for the dates that satisfy both conditions simultaneously. According to Arun: The wedding falls on one of the days between the 15th and 19th, which are: 16th, 17th, 18th. According to his mother: The wedding falls on one of the days between the 16th and 20th, which are: 17th, 18th, 19th. Comparing both sets: Arun: {16, 17, 18} Mother: {17, 18, 19} The common dates in both lists are the 17th and the 18th. Since we cannot narrow it down to a single specific day, the date is either the 17th or the 18th. Hence, option d.