What were initially used to help ships navigate safely?

To the one that i love i will never forget or hate just love me back

Lauses unnecessary to the meanings of the words modified demonstrative 2. clauses necessary to the meanings of the words modified relative 3. words for which pronouns stand intensive 4. a pronoun ending in -self and referring to the previously used noun or pronoun nonrestrictive clauses 5. a pronoun ending in -self and used for emphasis restrictive clauses 6. pronouns that ask questions indefinite pronouns 7. pronouns that point out to whom or to what the speaker is referring reflexive 8. everyone, nobody, and something are examples antecedents 9. pronouns introducing adjective or noun clauses interrogative 10. i, you, him, mine, and their are examples personal pronouns

Which choice is a major detail from paragraph two? a) the great wall is a large network of several walls and towers. b) the great wall looks like a long wall snaking its way across china. c) the great wall was constructed over hundreds of years beginning in 221 b. c. d) the great wall construction encouraged several independent kingdoms to unite.