SAT语法题两道,有关whereby的意思及用法

SAT语法题两道,有关whereby的意思及用法
第一题：
原句：Watermelons have been cultivated for more than 4000 years,(and whereby thumping them) to test for ripeness has an equally long history.
A 原句
B because thumping them
C whereby thumping them
D and thumping them
第二题：
原句：The name "transferware" (comes from a nineteenth-century technique for which) a pattern is engraved onto a copper roll,printed on tissue paper,and transferred onto earthware dishes.
A 原句
B comes from a nineteenth-century technique according to which
C comes from a nineteenth-century technique whereby
顺便说明一下whereby的用法.