Assume you use the SAS program

PROC SORT DATA = DATA_1; BY ID; RUN;

PROC SORT DATA = DATA_2; BY ID; RUN;

DATA second;

MERGE DATA_1 DATA_2;

BY ID;

RUN;

DATA_1

ID DATE

123 1/31/2013

456 9/15/2014

789 6/5/2015

DATA_2

ID DATE

123 9/5/2014

123 6/22/2014

333 2/9/2015

456 11/15/2013

Which of the following will happen?

a) The variable Date in DATA_1 will overwrite the variable Date in DATA_2 for observations with common ID values

b) The variable Date in DATA_2 will overwrite the variable Date in DATA_1 for observations with common ID values

c) Both Date variables will be included as separate variables

d) SAS will give you an error message