4. It can be inferred that the Republican Party was successful in establishingitself as a major party because
(A) its political program became essentially non-doctrinal in character
(B) the Whigs were unsuccessful in their attempts to steal from the Republicanplatform
(C) it was able to abandon its traditional opposition to slavery withoutalienating its regular supporters
(D) a more established party was simultaneously in decline
(E) it benefited from the experience of previous third parties that hadundergone similar transformations