The correct option is A way, death - Abstract Noun
Concrete nouns are physical objects, or people that can be perceived by at least one of our five senses: sight, touch, smell, taste, hearing. Abstract nouns are the opposite, they're ideas, concepts, states of being that cannot be perceived by any of our senses. In the sentence, 'way' is a manner or mode that leads to 'death'. Hence, it's an abstract noun as it cannot be perceived by even one of our senses. Similarly, 'death' is a state of being dead, it's an abstract noun. Hence option A is correct. Option B is incorrect because 'smoking' is a gerund (verbs that have -ing ending but perform the role of a noun) in the given sentence, and gerunds are considered to be abstract nouns and 'way' is not a physical path, but a manner that leads to death. Option C is incorrect because 'smoking' is not an abstract noun. Option D is incorrect because, firstly, 'smoking' is not a noun. Secondly, 'way' and 'death' are not concrete nouns, you can't see or touch a way, nor can you see or touch death, they're abstract nouns.