Assertion : Agrobacterium tumefaciens is popular in genetic engineering because this bacterium is associated with the roots of all cereal and pulse crops.

Reason : A gene incorporated in the bacterial chromosomal genome gets automatically transferred to the crop with which the bacterium is associated.

• If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion

• If both Assertion and Reason are true but the Reason is not the correct explanation of the assertion

• If Assertion is true but Reason is false.

• If both Assertion and Reason are false.

D.

If both Assertion and Reason are false.

Agrobacterium tumefacines is a gram negative, non sporing, motile, rod shaped bacterium, closely related to Rhizobium. It is commonly found on and around root surfaces.  

Rhizosphere seems to survive by using nutrients that leak from the root tissues. But it infects only through the wound-site either by naturally occurring or caused by transplanting of seedling and nursery stock. It is harmful to plants and useful to scientists for the same reason i.e, it transfers DNA into plant genomes found in soil worldwide.

A. tumefaciens cause crown gall disease of a wide range of dicot (broad leaved) plants especially members of rose family by transferring its own DNA into plant cells. But in laboratory, the ability to move all sorts of genes into plants has made the microbe the standard tool for investigating plant genetics and modifying crops.