Six persons J, L, R, O, X, and Z belong to a family and were born in six different years: 1978, 1982, 1995, 1997, 2013, and 2015. (All ages are calcul...

Six persons J, L, R, O, X, and Z belong to a family and were born in six different years: 1978, 1982, 1995, 1997, 2013, and 2015. (All ages are calculated as of the year 2018, and all are assumed to be born on the same date and month.) The difference in age between O and J is 18 years, and O is J's father. L is younger than R. X is not the oldest member of the family. R is not married to Z. Z was born in an even-numbered year. L is the only granddaughter of O's mother. O's father is 4 years older than O's mother. J is the son of R.

Four of the following five persons share a common characteristic and form a group. Which one does not belong to this group?

(a) O

(b) R

(c) X

(d) J

(e) L