The salinity of freshwater must be

Salinity is just the concentration of salts in water, so in freshwater its 0.5 ppt or less (parts per thousand) as a comparison the ocean has a salinity of 35 ppt. So fresh water has a little to no salinity

Hope this helps :)

The correct answer is - flagellated sperm.

Explanation:

In ancestral trait that is flagellated sperm in ferns that were limited to moist habitat has sperms that must swim to the eggs. This is why ferns often require splashing water for the movement of sperm to points near female gametangia during reproduction.

Fern now adapted the vascular system to get life on the life and they are not limited to the water bodies, however, flagellated sperm is the ancestral reproductive trait.