Google Cloud AI Platform provides tools and services for building, training, and deploying AI models at scale.
IBM Watson Developer Platform offers a range of AI and machine learning APIs and services for developers.
Infosys Nia is an AI platform that provides cognitive capabilities and automation solutions for enterprises.
Alexa is Amazon’s virtual assistant, which uses AI and voice recognition to perform tasks.
However, Alexa itself is not an AI development platform — it is an application that runs on AI technologies built by Amazon.
While developers can build Alexa skills, it is not a general-purpose AI development suite like the other options.
So, the correct answer is option (D) Alexa AI.