Study #1 Compares 2- and 4-Month Old Children on a Perceptual

Study #1 compares 2- and 4-month old children on a perceptual task. Study #2 uses the same task and compares four groups of children, aged 2, 4, 6, and 8 months. Which of the following is true?

A) study #2 is an direct replication
B) study #2 should not have tested the 2- and 4-month olds (already been done)
C) study #2 is a conceptual replication
D) study #1 should have tested 6- and 8-month olds