'Very' is used with only positive degree adjectives. So, it cannot be used with 'more' as it is a comparative degree adverb/adjective. Therefore, the highlighted part of the sentence is incorrect. Option (a) is also incorrect as per the above rule. We cannot use 'as' with 'more'. The correct structure is 'as + adjective/adverb + as'. 'So' is also used with only positive degree adjectives. Therefore, option (c) is also incorrect. 'Far' can be used with a comparative degree adjective. Thus, the phrase in option (d) is grammatically and contextually correct.
Hence, option (d) is the correct answer.
Note:
Adjectives: Words which are used with a noun/pronoun to describe or point out, the person, animal, place, or thing which the noun names, or to tell the number or quantity, are called Adjectives.
· The Positive Degree of an Adjective is the Adjective in its simple form. It is used to denote the mere existence of some quality of what we speak about. It is used when no comparison is made.
· The Comparative degree of an adjective denotes a higher degree of quality than the positive and is used when two things are compared.
· The Superlative degree indicates the highest degree of quality and is used when more than two things (or sets of things) are compared.