It's standard practice in many programming languages that if you need to include the string delimiter inside a string to use a double delimiter. So, you just need to double the single quote in your 'C&D''s'
,SUM (CASE WHEN Q2.CSISeqNo = 185 AND A.Description = 'Loan Cars - C&D''s Not Suitable' AND Q.Answer = 6
THEN 1 ELSE 0 END) AS [Parts ordering process]
J. Drew Allen
Business Intelligence Analyst