An otherwise healthy 24-year-old man presents with a painful ulcer on his tongue. The lesion is oval and measures approximately 3 mm in diameter. The lesion was not preceded by a blister. This problem has been cyclic (once per month), and the lesions have healed in about 1 week. He most likely has:

a. Minor aphthae
b. Major aphthae
c. Herpetiform aphthae
d. Secondary herpes
e. Erythema multiforme

A