During prophase l of meiosis, crossing over between the sister chromatids occurs. what is the purpose of the process?

Crossing over is a genetic phenomenon that occurs during meiosis and contributes to genetic mixing during reproduction. During cell division, pairs of homologous chromosomes associate, cross and then exchange certain segments of their genetic material, before separating. Some genes migrate from one chromosome to another.

Consequently, each of the gametes derived from the same precursor cell has a combination of genes different from those of the others. Thanks to the genetic mixing created by meiosis and fertilization, every zygote has a unique heritage of paternal and maternal genes (in different degrees). 
Crossing over can lead to an abnormal genome if the exchange is not done equally, which can lead to an in-utero death or congenital diseases.

The answer to this is b

Determine the cause of death for anna garcia

we need additional information in order to determine the cause of death for anna garcia. there are at least 3 things with explanation included as to why we need them are as follows:

there would be some predate medical situations.there would be a report about the cause that why she was there for backache from the hospital.there would be a report about what she injected in her thigh that she suffered from backache.