The correct option is
D Thomas Alva Edison is the most remarkable inventor in the world.
The words, 'Thomas', 'Alva' 'Edison' should be in a sequence as it refers to a single person.
The word, 'remarkable' is an adjective which describes the noun, 'inventor'. Hence, it precedes the word, 'inventor'. Hence, we have the phrase, 'remarkable inventor'. The word 'most', when placed before the word, 'remarkable', makes it a superlative adjective. Hence, we have the phrase, 'most remarkable inventor'.
When we use a superlative adjective (most remarkable) before a noun (inventor), it is usually preceded by the definite article, 'the'. Hence, the words, 'the most remarkable inventor' should come in a sequence.
The phrase, 'in the world' is an adverb phrase which describes the verb, 'is'.
So we have two grammatically correct sequences which form meaningful sentences:
(i) The most remarkable inventor in the world is Thomas Alva Edison; or
(ii) Thomas Alva Edison is the most remarkable inventor in the world.
(ii) above is given in option B, which is the correct answer.
Option A is incorrect as the phrase, 'in the most world' does not convey any meaning.
Option C: Any sentence beginning with the word, 'Is' has to be a question. However, there is no question mark at the end of the given sentence. Hence, this option is grammatically incorrect.
Option D is incorrect as adverbs of place (the phrase, 'in the world') have to be placed at the end of the sentence and not in the beginning.