A patient experiences pain and some gingival swelling in the anterior segment of the mandible. The mandibular lateral incisor has a shallow restoration, is tender to percussion and gives a positive response to the electric pulp tester. There is some mobility. The most likely diagnosis is:

Lateral periodontal abscess

Acute apical abscess

Acute serous pulpitis

Chronic ulcerative pulpitis

Acute suppurative pulpitis