What is about true about these atoms calcium, gold, argon, iodine

In moon rock sample the ratio of the number of stable argon-40 atoms present to the number of radioactive potassium−40 atoms is 7:1. Assume that all the argon atoms were produced by the decay of potassium atoms, with a half-life of 2.5×10^9yr. The age of the rock is

Explanation:

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the last one: artificial selection/genetic engineering

plant breeding is modifying the genetic composition of the plant - but this isn't cloning (which is specifically introducing a gene into a genome). but you are artificially selecting for the phenotype that you want.

the second one is literally genetic engineering - the gene would have been cloned first and then inserted or genetically engineered into the new plant cell (the cotton).