On January $1,2020,$ Solis Co$.$ issued its $10\%$ bonds in the face amount of $$8,000,000,$ which mature on January $1,2030.$ The bonds were issued for $$9,080,000$ to yield $8\%,$ resulting in bond premium of $$1,080,000.$ Solis uses the effective$-$interest method of amortizing bond premium. Interest is payable annually on December $31.$ At December $31,2020,$ Solis's adjusted unamortized bond premium should be

a$.$ $$1,080,000.$

b$.$ $$1,006,400.$

c$.$ $$972,000.$

d$.$ $$812,000.$