A Baby Weighed $5$ Lb $6$ Oz at Birth $6$ Lb $9$ Oz Find the Baby's Increase in Weight During the 6

A baby weighed $5$ lb $6$ oz at birth. At 6 months of age, the baby weighed $6$ lb $9$ oz. Find the baby's increase in weight during the 6 months.

A) $2$ lb $5$ oz
B) $3$ lb $4$ oz
C) $1$ lb $3$ oz
D) $4$ lb $7$ oz
E) $5$ lb $6$ oz