Question

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

Explanation:

HeLa cells are cancerous cells. Cancer cells often have abnormal karyotypes. Telomere length is not directly related to karyotype in the context of this question. Normal human cells have 46 chromosomes (23 pairs). HeLa cells do not have fewer chromosomes. They do not lack multiple pairs of chromosomes. However, cancer cells like HeLa cells can have aneuploidy (abnormal number of chromosomes). But among the options, the key is that HeLa cells (as cancer cells) can have multiple copies of some chromosomes (not every chromosome in a strict sense, but compared to the other options this is the most relevant as it indicates karyotype abnormality).

Answer:

They have multiple copies of every chromosome.