Self-study
Pollen and other allergens can cause cells in the nose to release histamine, a chemical that inflames nasal tissue and causes runny nose, congestion, and sneezing. ██████████████ ████████ █████ ███████ ████████ ██ ████████ ███ ██████ ██ ██████████ ██ █████████ ██████████████ ████ █████ ████████ █████████ ███████████ ████████ █████████ █████ ██ ████ ██ ███ █████████ ██ █████ █████ ███████ █████ █████████
Summary
Pollen/allergens can cause cells in nose to release histamine.
Histamine causes certain allergy symptoms.
Antihistamines can reduce these allergy symptoms by blocking the action of histamine.
Antihistamines also have other effects. One of those effects is drowsiness.
Histamine doesn’t play any role in how colds produce symptoms.
Notable Valid Inferences
We’re looking for what must be true. This set of facts doesn’t produce any obvious inferences, so I’d mainly rely on process of elimination.
19.
If the statements above are █████ █████ ███ ██ ███ █████████ ████ ████ ██ █████
a
Pollen and other █████████ ██ ███ █████ ██████
Could be false. We know that histamine doesn’t play role in how colds produce symptoms. But what causes colds? We don’t know that pollens and allergens don’t cause colds.
b
Colds are more █████████ ██ █████ ████ ██████████
Could be false. We don’t know what’s more difficult to treat. Although antihistamines can reduce allergy symptoms, that doesn’t mean allergies are easier to treat than colds. Maybe antihistamines can also reduce cold symptoms, or there are other things that can treat colds.
c
Antihistamines, when taken ██████ ███ ███████████ ███████ ██████████ ██████ ██ ██████
Could be false. We were told antihistamines have “other effects.” Those effects might include reducing cold symptoms; we don’t know. Although histamines aren’t part of cold symptoms, antihistamines might still reduce those symptoms through some means besides blocking histamines.
d
The sleeplessness that █████████ ███████████ █████████ ███ ██ ███████████ ███████ ████ ███████████████
Could be false. We don’t know whether antihistamines can “effectively treat” sleeplessness. Although antihistamines can cause drowsiness, that doesn’t guarantee that they can treat sleeplessness.
e
Any effect antihistamines ███ ████ ██ ████████ ████ ████████ ████ ███ ██████ ████ ████████ ███ ██████ ██ ██████████
Must be true. Histamines play no role in how colds produce symptoms. So, if antihistamines can reduce cold symptoms, it won’t be through blocking histamines. It would be through some other mechanism that’s related to producing cold symptoms.