My friends live in . . . . . . . . old house in . . . . . . . . small village. There is . . . . . . . . beautiful garden behind . . . . . . . . house. I would like to have . . . . . . . . garden like that.

The first sentence has an 'old house' mentioned. It's not specified which house, it could be any old house, and hence an indefinite article is required. The phrase 'old house' begins with a vowel, so the article pertaining to such nouns is 'an' which is the correct answer. Similarly, 'small village' and 'beautiful garden' require an indefinite article 'a' since they both begin with a consonant. In the second sentence, 'house' is mentioned for the second time, by now we know which house is being referred to, hence we use 'the' and not 'a'. In the third sentence, 'garden' is not the same garden that the speaker's friends have, but just any garden like the one mentioned before. This means we're supposed to use 'a' in the last sentence. The option containing all these correct articles is option B.