The number of distinct prime factors of the largest 4-digit number is

1. 2

2. 3

3. 5

4. none of these

The number of distinct prime factors of the smallest 5-digit number is

1. 2

2. 4

3. 6

4. 8

Which of the following is a pair of co-prime numbers?

1. 8, 45

2. 3, 18

3. 5, 35

4. 6, 39

Every natural number has an infinite number of

1. prime factors

2. factors

3. multiples

4. none of these