Symptoms associated with cryptosporidiosis, cyclosporiasis, and isosporiasis are NOT pathognomonic.  This means _____.

(a) Infections are generally asymptomatic
(b) Symptoms are not sufficiently specific for a particular disease to guide the diagnostic tests toward a particular parasite
(c) Parasites are only found when overt symptoms are present
(d) Existing laboratory tests will not be useful in diagnosing the infection caused by the parasites listed