Answer
Abolitionist increased their efforts to end slavery
Explanation:
Biplanes (and triplanes) became (nearly) extinct not because high strength materials (like composites) were not available, but because they became available.
One of the major reasons for use of biplanes in the early days of aviation was that the materials available were of insufficient strength for the (wing) designs used.
The major disadvantage of biplanes (or triplanes) is aerodynamic- it produces a lot of drag compared to the monoplane and the wings interfere with each other.
So, the biplane was an (aerodynamically) inefficient solution to a structural problem. As higher strength materials like Aluminum became widespread, the biplanes fell out of favor.
While they <em>can</em> be revived, I don't see why someone would do that, except for nostalgia (or some special uses, like aerobatics).
There are some companies who manufacture or restore biplanes, but they usually don't use (modern materials like) composites, though modern avionics are used.
Answer:
B) The courts interpretation of whether the Equal protection clause allowed racial segregation.
Explanation:
In the Plessy vs. Ferguson case (1896) the Supreme Court justices ruled that "separate but equal" facilities for blacks and white citizens were not a violation of the equal protection clause of the 14th amendment. This allowed for segregated public and private facilities within the US for the next 6 decades.
This all changed with the Brown vs. Board of Education case (1954). In this case, the Supreme Court judges overruled the Plessy vs. Ferguson case and stated that "separate but equal" is a direct violation of the 14th amendment.
A. monopoly
used to be very popular in steel and oil