It is easier P : to venture into space Q : for men R : beneath their feet S : than to explore The Proper sequence should be:

The correct answer is D. PQSR.

The sentence is about the difficulty of exploring the Earth compared to exploring space. The first word, “It,” is the subject of the sentence. The verb of the sentence is “is,” which is followed by the adjective “easier.” The adverbial clause “to venture into space” modifies the adjective “easier.” The noun phrase “for men” is the object of the preposition “to.” The prepositional phrase “beneath their feet” modifies the noun “men.” The verb phrase “to explore” is the object of the preposition “than.” The noun phrase “the Earth” is the object of the verb “to explore.”

The correct sequence of the words is:

1. It
2. is
3. easier
4. for men
5. to venture into space
6. than
7. to explore
8. the Earth

The other options are incorrect because they do not follow the correct grammatical order of the words.