Sea-floor spreading is a valuable theory as it relates to plate tectonics because
a. it replaced plate tectonics as the main theory explaining geologic processes.
b. it disproved the theory of continental drift by providing evidence that tectonic plates cannot move vast distances.
c. it was combined with the theory of continental drift to form one unified explanation.
d. it showed how the spreading of the ocean floor can cause earthquakes, which explained continental drift.

we need to see the statements.

#1  sara was always tasked with selecting birthday presents for her friends and family because everyone admired her  impeccable taste. 

impeccable (adj): perfect, flawless

#2  they moved to the united states many years ago, but their  insular  attitudes made it difficult for them to socialize. 

insular (adj): isolated; separate

#3  the professor explained the  semantic  relationship between the two nouns used in the sentence. 

semantic (adj): related to words or the meanings of words 

happy to : )