Explanation:

The Factories Act, 1948 defines terms for categorizing young people in an industrial setting:

- Option 1: Who has completed 15 years of age but is less than 18 years - This definition is correct for an "Adolescent" under the Factories Act, 1948. An adolescent is someone who is over 15 but under 18, and they are subject to specific employment rules within factories. Correct Answer

- Option 2: Who is less than 18 years - It's not specific enough to define an adolescent.

- Option 3: Who has completed 14 years of age but is less than 18 years - This is incorrect regarding the Factory Act definition for the adolescent category.

- Option 4: Who has completed 16 years of age but is less than 18 years - Too narrow to fit the legal description under the Act.