Problem fixed using the below code and adding the as col1 highlighted

--File 2 OPTION.txt

SELECT DISTINCT

B12.MODLN_USC_C + ';' +

LEFT(ENT_ENTITY_C, 1) +

SUBSTRING(ENT_ENTITY_C, 3, 1) +

SUBSTRING(ENT_ENTITY_C, 6, 1) +

SUBSTRING(ENT_ENTITY_C, 4, 1) +

SUBSTRING(ENT_ENTITY_C, 5, 1) + ';' +

b10Opt.USC_C + ';' +

LTRIM(RTRIM(ISNULL(B10Opt.USC_DESC_X, ''))) as col1

FROM

(select ent_entity_c, modln_usc_c, ent_opt_usc_c

from CDMStaging..mfslb12_entlst

where MKT_C = 'FF' AND ENT_STATUS_C IN ('O','B')) AS b12

INNER JOIN

(SELECT usc_c, usc_desc_x

FROM CDMStaging..mfslb10_elm

where mkt_c = 'FF') As B10Opt

on CHARINDEX(B10Opt.usc_c, B12.ENT_OPT_USC_C) > 0

ORDER BY 1