You have created an HTTP(S) load balanced service. You need to verify that your backend instances are responding properly. How should you configure the health check? 

Answer options:

A. Set request-path to a specific URL used for health checking, and set proxy-header to PROXY_V1. 
B. Set request-path to a specific URL used for health checking, and set host to include a custom host header that identifies the health check. 
C. Set request-path to a specific URL used for health checking, and set response to a string that the backend service will always return in the response body.
D. Set proxy-header to the default value, and set host to include a custom host header that identifies the health check.

B

Reference: https://cloud.google.com/load-balancing/docs/health-checks