Question

how do hela cells differ from normal cells in terms of karyotype?
they have multiple copies of every chromosome.
they have fewer chromosomes.
they have shorter telomeres than normal.
they lack multiple pairs of chromosomes.

Explanation:

HeLa cells are cancerous cells. Cancer cells often have abnormal karyotypes. Normal human cells have 46 chromosomes (23 pairs). HeLa cells have multiple copies of some chromosomes (aneuploidy), not all chromosomes (not polyploidy). They do not have fewer chromosomes than normal human cells (normal is 46, HeLa has more in most cases). Telomeres in HeLa cells are not shorter (they have telomerase which maintains telomere length). And they do not lack multiple pairs (they have extra in many cases).

Answer:

They have multiple copies of every chromosome.