Metals are solid except: 

The periodic table contains metals, which have a variety of characteristics, including being good conductors of electricity and heat. They have a metallic connection and are solid and glossy in appearance.

Metals: Metals are elements that may be found in the periodic table and have a variety of characteristics, such as being excellent heat- and electricity-conductors. They have a metallic connection and are solid and glossy in appearance.
The existing metals are all solid by nature. Only Mercury, which is naturally liquid, is an exception.
Metals are solid, with the exception of Mercury.

Hence, the correct option is (b) Mercury.