Which best identifies the underlined clause?
these flower fossils, which came from a vacant lot, are the best that have ever been discovered anywhere in the world.
a.
independent clause
b.
adjective clause
c.
noun clause
d.
adverb clause

B.
adjective clause

which came from a vacant lot

Adjective clauses modify the noun or the pronoun in the sentence's main clause. The first thing to do is to identify the two clauses in the sentence.

First clause: Those may enter the park (the main clause)
Second clause: whose tickets have been punched (the subordinate clause)

Since adjective clauses generally start with a relative pronoun, it is clear that the second clause is the adjective clause. The relative pronoun is "which". Another clue is that adjective clauses are always the subordinate clause. It modifies the pronoun those.