Final answer:
The smallest natural number by which 135 must be divided to obtain a perfect cube is 9.
Step-by-step explanation:
To find the smallest natural number by which 135 must be divided to obtain a perfect cube, we need to factorize 135.
The prime factorization of 135 is 3 x 3 x 3 x 5. We see that we have three 3's, so we need one more factor of 3 to make it a perfect cube. Therefore, the smallest natural number by which 135 must be divided is 9. Hence, the answer is (d) 9.
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