You plan to use Azure Cognitive Services for the persistence of searchable data using indexes. To execute the search operations, you use Azure.Search.Documents SDK client library. Which client type would you use with Azure.Search.Documents client library to search your indexed documents, auto-completing search terms and updating documents to an index?

Answer options:

A.SearchClient
B.SearchIndexClient
C.SearchIndexerClient
D.SearchOptions

Correct Answer: A 
Option A is correct because you use SeachClient as the client type with Azure.Search.Documents client library to: 
Searching 
Autocompleting 
Suggesting 
Adding, updating, or deleting documents 
Option B is incorrect because the SearchIndexClient client type is used for configuring a search index. 
Option C is incorrect because the SearchIndexerClient client type is used for creating indexers and skillsets. 
Option D is incorrect because the SearchOptions is not one of the client types. It is a class offered by Azure.Search.Documents to provide parameters for search queries such as filtering, sorting, faceting and paging. 
Reference: To learn more about the Azure Cognitive Search client library, use the link given below: 

https://docs.microsoft.com/en-us/dotnet/api/overview/azure/search.documents-readme