And when he was gone forth into the way, there…

Please can you shed some light on this for me please ?
Jesus is God and God is good ! Why does Jesus say “ Why callest thou me good? there is none good but one, that is, God”

“And when he was gone forth into the way, there came one running, and kneeled to him, and asked him, Good Master, what shall I do that I may inherit eternal life? And Jesus said unto him, Why callest thou me good? there is none good but one, that is, God.”
‭‭Mark‬ ‭10:17-18‬ ‭KJV‬‬

And when he was gone forth into the way, there came one running, and kneeled to him, and asked him, Good Master, what shall I do that I may inherit eternal life? And Jesus said unto him, Why callest t