Which of the following metal salts give a red and opaque borax bead in the reducing flame (in cold)?

Cu metal salts give a red and opaque borax bead in the reducing flame.

Cupric metaborate, which is red and opaque, is transformed into metallic copper in a reducing flame.

When it is heated in a platinum wire loop. Borax expands and creates a clear, colourless glassy bead. This hot bead takes on a distinctive colour when it comes into contact with a little quantity of coloured salt and is heated once again