Corrected versions:
A) The road curved sharply; she swerved into a fence. (or use a conjunction: The road curved sharply, and she swerved into a fence.)
B) Joe is a computer whiz; he is also a crackerjack programmer. (or use a conjunction: Joe is a computer whiz, and he is also a crackerjack programmer.)
C) Brahms wrote four symphonies; each one is superb. (or use a conjunction: Brahms wrote four symphonies, and each one is superb.)
D) From the oven came an aroma of chocolate and honey. (S)