。
She rejected our proposal.
Literal
She [topic-は] our proposal [object-を] rejected.
拒絶する ('to reject, to refuse') is a sharper, more formal verb than 断る — 拒絶 carries connotations of outright rejection rather than polite declining. The kanji 拒 ('refuse') and 絶 ('cut off') reinforce the absolute nature of the refusal. You'd see 拒絶 in legal, business, or dramatic contexts; in casual speech, 断る is far more common. Compare with 拒否する ('to refuse') — slightly less harsh than 拒絶 but still firmer than 断る.