Regarding pureline selection,which statement is most correct?

Potato varieties produced for crops are

Which of the following genes,when transferred from wild species to cultivated crops,are considered beneficial for hybridization?

The greatest genetic diversity of plants is found in:

Four inbred lines of maize are crossed. This type of cross is known as:

Consider the following four measures $(1-4)$ that could be taken to successfully grow chickpea in an area where bacterial blight disease is common.
$(1)$ Spray with Bordeaux mixture
$(2)$ Control of the insect vector of the disease pathogen
$(3)$ Use of only disease-free seeds
$(4)$ Use of varieties resistant to the disease
Which two of the above measures can control the disease?