With an lit. question !
all of the following statements concerning compound sentences are true except:
a. they're often connected with a coordinating conjunction.
b. they're often two complete clauses joined by a comma
c. they're often connected with a semicolon
d. they include at least two complete or independent clauses.
e. they allow you to vary sentence structure in your writing.

- "the answers are a and b.  

when cullen speaks of planting while others reap, and standing "abject and mute," he is speaking about the racial injustices present in american society. as these injustices have changed over time, the american identity  has also shifted. those changes are, in turn, reflected in american literature."

comfortable

explanation:

one type of the adjectives is predicate adjective. a predicate adjective is an adjective which follows a linking verb and modifies or refers back to the main subject of that linking verb.

it usually is used just before the noun it modies.

here in this example:

'penguins seem comfortable in the coolest habitats', comfortable is the predicate adjective which follows the linking verb 'seem' and modifies the noun.