In the mandibular dental arch of a 12-year old boy, the permanent first molars are in contact with the first premolars and the crowns of the second premolars have erupted lingually. The likely cause is

premature loss of deciduous second molars

faulty lingual eruption of the second premolars.

teeth too large for the dental arch.

lack of space.

ankylosis of the mandibular second premolars.