What must be the product of two odd numbers? A odd number B even number C prime number d combined number, please give an example

It must be an odd number, 3 * 7 = 21, 7 * 13 = 91. The reason for the error is that the odd number has 1, and 1 * 7 = 7 is prime

1. In 5, 2, 8, 20, 11, 15, 1 and 30, the natural number is [], the even number is [], the odd number is [], the prime number is [], and the combined number is []
The unit of fraction is one tenth. The sum of all the simplest true fractions is []

Natural numbers are 1, 5, 2, 8, 20, 11, 15, 30 [8], even numbers are 2, 8, 20, 30 [4], odd numbers are 1, 5, 11, 15 [4], prime numbers are 5, 2, 11 [3], and combined numbers are 8, 20, 15, 30 [4]
The unit of fraction is one tenth. The sum of all the simplest true fractions is [2]

In 1.2,0,4,30,17,15,1,18, integers have (), even numbers have (), odd numbers have (), composite numbers have (), prime numbers have ()

Integers are (0,4,30,17,15,1,18)
Even numbers have (0,4,30,18)
Odd numbers have (17,15,1)
The total number is (4,30,15,18)
Prime number has (17)

Write all prime numbers within 100 and 15, where the odd number has () and the even number has ()
At least adding () is a multiple of three; at least adding () is a multiple of two and a multiple of five
There are () ways to fill in a number in 2 × 5 so that it is a multiple of three
If there are three consecutive even numbers, the middle one is a, then the other two can be expressed as (), ()

At least (2) is a multiple of three; at least (4) is a multiple of two and a multiple of five
There are (3) ways to fill in a number in 2 □ 5 so that it is a multiple of three
If there are three continuous even numbers, the middle one is a, then the other two can be expressed as (A-2), (a + 2)

What must be the product of two odd numbers? A odd number B even number C prime number d combined number, please give an example