Sonora-$64$ and Lerma Rojo-$64$ were brought to India from Mexico and modified through
A) UV-rays
B) X-rays
C) $\beta$ - rays
D) $\gamma$ - rays

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Hint: Sonora-$64$ and Lerma Rojo-$64$ are mutant dwarf varieties of wheat.

Complete Answer:
- Sonora-64 and Lerma Rojo-64 were developed in Mexico and then modified to produce a more beneficial mutant by using gamma rays.
- These varieties are high yielding so can meet the increasing requirement of food. These varieties also have several other benefits such as they are resistant to lodging and diseases.

So, the ‘$\gamma $− rays are the correct answer.

Additional information:
- The mutant varieties brought from Mexico were Sonora $64$, Lerma Rojo $64$-A, Sonora $63$, Mayo $64$, and \[S\text{ }227\] .
- These varieties are produced from the hybridization of Mexico traditional wheat varieties with other varieties such as Norin 10. These were then brought to India for testing their products.
- $\gamma$ rays are low wavelength electromagnetic radiations emitted during radioactive decay of the nucleus. These rays are used to induce mutations in the crops to form new varieties.

- UV-rays are generally used in the sterilization processes to kill microorganisms from anything.
- Alpha radiation is the most dangerous because it is easily absorbed by cells. Beta and gamma radiation are not as dangerous because they are less likely to be absorbed by a cell and will usually just pass right through it.
- Beta rays are not used to create the mutants. Gamma rays are used for this purpose.