Aside from the Density of Dinoflagellates in P

Multiple Choice

Aside from the density of dinoflagellates in P. ianthina skin, how many of the following factors can affect whether or not the endosymbiotic dinoflagellates promote the sea slug's survival (assuming latitudes above or below Earth's equator) ?
1) day length
2) height of sun above the horizon
3) cloud cover
4) depth at which P. ianthina lives
5) water clarity

A) two of these
B) three of these
C) four of these
D) five of these