Concept:A number + noun joined by a hyphen before another noun is a compound adjective, and its noun stays singular with no apostrophe.Solution:We say "a ten-year-old boy", "a five-kilometre race", so: "I faced a seven-member panel.""Panel" is a singular countable noun, so it also needs the article a. Options A, C and D add a plural -s or a possessive 's, which are wrong.Answer:Option B (a seven-member)