Read the following excerpt. Using the context of the paragraph, select the word that best completes the sentence.

If the adolescent fails to resolve the identity crisis by the time of entry into adulthood, he will feel a sense of role confusion or identity diffusion. Others seem to avoid the crisis altogether and settle easily on an available, socially approved identity. Still others resolve their crises by ___________ an available but socially disapproved ideology. This latter option is called negative identity formation and is often associated with delinquent behavior. Resolution of the adolescent identity crisis has a profound influence on development during later adulthood.

lacking 
missing
finishing
adopting