3. (3 points) Among all the integers formed without repeating digits using the four digits $1,3,4$ and 6, the number of integers that are multiples of 6 is
A. 1
B. 2
C. 3
D. 4
【Analysis】According to the characteristics of numbers divisible by 2, the unit digit is 4 or 6; when the unit digit is 4, according to the characteristics of numbers divisible by 3, it can be concluded that among all the integers formed by the other three digits without repetition, there are no multiples of 3; when the unit digit is 6, according to the characteristics of numbers divisible by 3, it can be concluded that among all the integers formed by the other three digits without repetition, there are multiples of 3, which are 6 or 36.

【Solution】Solution: As analyzed, among all the integers formed by the four digits $1,3,4$ and 6 without repetition, the numbers that are multiples of 6 are 36 and 6.

Therefore, the correct answer is: B.