Different technical terms are used for different types of hairs, which will be used to describe the hairs on these particular flowers depends on what these hairs are like in each case. Often plant parts will have more than one kind of hair present.

The technical botanical term is 'trichome', but that just describes a generalized plant appendage - it can include plant hairs, root hairs and a variety of other similar growths. There are many more terms to describe the type or appearance of these hairs including glabrous, hirsute, tomentose, downy, pubescent, etc. Several basic functions or advantages of having surface hairs can be listed - keeping grazing predators at bay, repelling some insect pests, a method of attachment to support structures/organisms, a method of (modest)cold protection, reflecting heat, collecting available moisture in very dry or arid climates and protecting against surface winds, thereby reducing evaporation. Sometimes multiples of these tasks are accomplished depending on where the hairs are located, their density and specific structure.

Try Googling 'trichomes' for additional details :-)

The correct answer is C.

Thanks all for the responses.
gardengal48--Great info! I did Google "trichomes" and it was very helpful.