The signature of the BIT among India and Uzbekistan nations will upgrades economic cooperation and deep the investment environment.

Explanation

The correct answer is (a): signing, between, enhance, strengthen. Original Sentence: "The signature of the BIT among India and Uzbekistan nations will upgrades economic cooperation and deep the investment environment." Analyzing the highlighted words: 1. "Signature": o The word "signature" is incorrect in this context because it refers to a physical act of signing rather than the formal process or agreement itself. "Signing" is more appropriate because it refers to the action of formally agreeing to a treaty or agreement. 2. "Among": o "Among" is incorrect because it is used when referring to more than two entities. Since the sentence refers to only two countries, the correct preposition should be "between." 3. "Upgrades": o The verb "upgrades" is incorrect here because "will" should be followed by the base form of a verb. "Enhance" is the appropriate base form, meaning to improve or increase in value. 4. "Deep": o The word "deep" is incorrect here because it is an adjective, but we need a verb. The correct verb is "strengthen," meaning to make something stronger or more effective, which fits the context of improving the investment environment. Now, considering all these corrections, let's look at the options: • (a) signing, between, enhance, strengthen: Correct. All replacements fit both grammatically and contextually. • (b) registering, amongst, enrich, toughen: Incorrect. "Registering" and "amongst" are incorrect, and "toughen" doesn't fit. • (c) subscribing, amidst, better, fortify: Incorrect. "Subscribing" and "amidst" are incorrect. • (d) inking, through, improve, intensity: Incorrect. "Inking" and "through" don't work here, and "intensity" is not a verb. Corrected sentence: The signing of the BIT between India and Uzbekistan nations will enhance economic cooperation and strengthen the investment environment.