The best answer to fill the gap is A. in spite of. This is because the sentence is a type of sentence called a concession.

A concession is a sentence that acknowledges or admits a point or fact that goes against one’s main argument or opinion. The structure of a concession is:

• Main clause, concession clause
• Concession clause, main clause

The first part of the sentence (Attention has shifted to the teaching of science nowadays) is the main clause, which expresses the main idea or argument of the speaker or writer.

The main clause uses the present perfect tense, which shows that the action or situation started in the past and has a connection to the present.

The second part of the sentence (… the usefulness of the Arts) is the concession clause, which expresses the point or fact that contradicts or weakens the main idea or argument.

The concession clause uses the noun phrase the usefulness of the Arts, which shows the positive value or benefit of the Arts.

The gap is a word or phrase that introduces the concession clause and shows the contrast or opposition between the two clauses.

The word or phrase should be a preposition or a conjunction that can be followed by a noun phrase.

The correct word or phrase is in spite of, which means despite or regardless of. The other options are incorrect because they do not show the contrast or opposition between the two clauses.

Not minding means not caring or paying attention to something, but it is not a preposition or a conjunction that can be followed by a noun phrase.

Oblivious to means unaware or ignorant of something, but it is an adjective that modifies a noun or a pronoun, not a word or phrase that introduces a clause.

Forgetting means failing to remember or recall something, but it is a verb that has a subject and an object, not a word or phrase that introduces a clause.