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Number theory Difficulty 3.0 AMC 10/12 Find the answer United Kingdom

Sonia wants to write a positive five-digit integer whose digits are 1, 2, 3, 4 and 5 in some order. The first digit of the integer is to be divisible by 1, the first two digits are to form a two-digit integer divisible by 2, the first three digits are to form a three-digit integer divisible by 3, the first four digits are to form a four-digit integer divisible by 4 and the five-digit integer itself is to be divisible by 5. How many such five-digit integers could Sonia write?

(A) 1010 (B) 55 (C) 22 (D) 11 (E) 00

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