Which best describes the way photographs are considered by historians?
a. primary source documents that are useful in the study of history
b. reliable sources for the study of history only if from a named source
c. secondary source documents that are useful in the study of history
d. unreliable sources for the study of history because they are too subjective
e. useful sources for the study of personal histories, but not for general history

two factors or characteristics of a chapter that might make it difficult to read would be words i don't understand, or if i don't fully understand what's going on in the chapter. strategies i can use to get through the difficult material would be a dictionary, and re-reading previous chapters to get a better grasp of what the author is trying to say.

the legal limit for the drivers who can drive after consuming any amount of alcohol is 21 years.

explanation:

on november 1, 1996, a "zero tolerance law" was put into effect in the new york state.

according to this zero tolerance law, for people under the age of 21 years, it was illegal to purchase and possess alcohol or to drive after consuming any amount of it.

also, the alcohol involvement rate for the drivers under the age of 21 was roughly twice that of elderly drivers.