With Howells, James, and Mark Twain active on the literary scene, ______ became the major trend in American literature in the seventies and eighties of the 19th century.

A．the rose
B．the thistle
C．the daffodil
D．the shamrock

A．petrological research report focused on the history of temperature-depth records in the United States
B．congressional report urging the conservation of oil and natural gas reserves in the United States
C．technical journal article concerned with tile recoverability of remaining coal resources
D．consumer report describing the extent and accessibility of remaining coal resources