The Direction of Shell Coiling in Snails Such as Limnea

Multiple Choice

The direction of shell coiling in snails such as Limnea peregra is determined by the egg's genotype,which affects orientation of the spindle in early cleavage divisions.How could the egg genotype cause the directional orientation of a spindle in the embryo?

A) by products of mitochondrial genes that pull the centrioles toward the mitochondrial position
B) by attachment of spindle fibers to mitochondria at the edges of the cell
C) by maternally directed placement of mRNAs and proteins at appropriate positions in the egg cytoplasm
D) by the release of maternal mitochondrial genomes into the egg cytoplasm
E) by zygotic gene activation due to maternal mitochondrial genes