"A lathe is being worked on$.$ A rack and pinion gear system is installed with an excess backlash clearance of $0\mathrm{.}020$ in$.$ What is done to correct the problem?" $$ A$.$ Shim rack $0\mathrm{.}020$ in$.$ and pinion $0\mathrm{.}000$ in$.$ B$.$ Shim pinion $0\mathrm{.}020$ in$.$ and rack $0\mathrm{.}000$ in$.$ C$.$ Shim pinion $0\mathrm{.}010$ in$.$ and rack $0\mathrm{.}010$ in$.$ D$.$ Shim rack $0\mathrm{.}018$ in$.$ and pinion $0\mathrm{.}000$ in