Since f is positive I would say f
The answer to this question would be D. Hydrophilic.
The word hydrophilic mean attracted by water. That means the molecule has a force to attract water molecule, thus be able to dissolve in water. The polarity of the molecule would determine whether a molecule hydrophilic or not.
Its opposite would be hydrophobic which the molecule can't dissolve in water. One example of this would be oil or fat. That is why sometimes it is called lipophilic too.
Not 100% sure if its right.
When an object covers equal distances in equal amounts of time, it is moving at a constant speed.