Maintained for two decades by a single unpaid volunteer, the compression library attracts almost no public notice, although its importance is wildly (i) ______ to its visibility; buried inside millions of programs, from banking systems to spacecraft, it has become the unacknowledged (ii) ______ of the digital economy, and its failure would ripple outward faster than anyone could trace.

Blank (i)	Blank (ii)
A. subordinate	D. appendage
B. germane	E. bellwether
C. disproportionate	F. linchpin