‘ ’
The quote within the quote — and the apostrophe the keyboard never had.
‘ opens (U+2018) and ’ closes (U+2019), and the second one holds two trades: closing the single quotation and serving as the typographic apostrophe — it’s, rock ’n’ roll.
The keyboard's straight apostrophe is a typewriter character; Unicode recommends U+2019 as the preferred apostrophe. The entities are ‘ and ’.
Wrong: it's · rock 'n' roll
Right: it’s · rock ’n’ roll