Meaning: 'Stinging' refers to something that causes sharp discomfort or pain, often used metaphorically to describe pressing issues.

Wrong options:

• slanting: Slanting refers to something that is tilted or not straight, which does not relate to the nature of the problem described.
• stalling: Stalling implies delaying or stopping progress, which does not accurately capture the nature of the problem being discussed.
• shafting: Shafting means to cheat or deceive someone, which is not relevant to the context of waste disposal.

Correct answer: sustainable

Explanation: The term 'sustainable' is appropriate as it indicates that the waste management solutions should be viable in the long term, fitting well with the context of environmental and social acceptability.

Meaning: 'Sustainable' means capable of being maintained over the long term without harming the environment or depleting resources.

Wrong options:

• unattainable: Unattainable means something that cannot be achieved, which contradicts the goal of effective waste management solutions.
• objectionable: Objectionable refers to something that is offensive or unacceptable, which does not align with the desired characteristics of waste management solutions.
• treasonable: Treasonable relates to betrayal of one's country, which is irrelevant in the context of waste management.

Correct answer: authorities

Explanation: The word 'authorities' is suitable as it refers to the governing bodies responsible for managing waste in cities, making it contextually and grammatically correct.

Meaning: 'Authorities' refers to the people or organizations that have the power to make decisions and enforce rules, particularly in governance.

Wrong options:

• plants: Plants refer to living organisms that produce energy through photosynthesis, which does not relate to the management of waste.
• culture: Culture refers to the social behavior and norms found in human societies, which is not the focus of waste management issues.
• history: History refers to past events, which does not pertain to the current challenges faced by cities in waste management.

Correct answer: handling

Explanation: The term 'handling' is appropriate as it refers to the management and treatment of solid wastes, fitting well within the context of waste disposal technologies.

Meaning: 'Handling' means the process of managing or dealing with something, in this case, solid wastes.

Wrong options:

• reserving: Reserving means to keep something for future use, which does not apply to the context of waste management.
• preserving: Preserving refers to maintaining something in its original state, which is not relevant to the active management of waste.
• deserving: Deserving means being worthy of something, which does not fit the context of waste management.

Correct answer: composed

Explanation: The word 'composed' fits grammatically as it indicates that the organic solid waste is made up of various components, aligning with the context of the sentence.

Meaning: 'Composed' means made up of or formed from various parts or elements.

Wrong options:

• disposed: Disposed means to get rid of something, which does not accurately describe the composition of organic solid waste.
• composing: Composing refers to the act of creating or forming something, which is not the correct usage in this context.
• disposing: Disposing means to throw away or get rid of something, which does not fit the context of describing what organic solid waste consists of.