What happens if one cultures cells from a tumor lacking a functional rb gene after reintroducing a wild-type copy of the gene into those cells? 1) the cancer phenotype remains. 2) the cancer phenotype is more extreme. 3) the cancer phenotype disappears. 4) the cells immediately die.

The cancer phenotype disappears.

Explanation:

The Rb gene here represents the a protein which is a tumor suppressor protein that is non-functional in several major cancers.

One of the function of Rb is to prevent the excessive growth of the cell by inhibiting the excessive cell growth by hindering the cycle progression until the cell is itself ready for division.

If the functional Rb gene is reintroduced in a wild type copy of cells there would be no cancer in the cells. No phenotypic cancer will appear in the cells.

So, the correct answer would be Option C  

the organisms are not adapted to live in some communities or habitats.

the answer is d. none of the above