Answer:

A number with only two factors is called a prime number. A number with more than two factors is called a composite number. The number 1 is neither prime nor composite. It has only one factor, itself

Factors of 73: 1, 73

Factors of 75: 1, 3, 5, 15, 25, 75

Factors of 77: 1, 7, 11, 77

Factors of 81: 1, 3, 9, 27, 81

answer : 1)73