Gadgets
Producers	Marginal Cost
ABC Inc.	$2
DEF Corp.	$4
GHI Inc.	$6
JKL Corp.	$8

If the price of Gadgets is $4 then all else the same, the producers for Gadgets will be [choose one] ["GHI Inc., JKL Corp.", "ABC Inc.", "ABC Inc., DEF Corp.", "DEF Corp., GHI Inc., JKL Corp."]

If the price of Gadgets is $4 and each producer can only make one Gadget, then the producer surplus is [choose one] ["$6 and 2 Gadgets are produced.", "$0 and 1 Gadget is produced.", "$2 and 1 Gadget is produced.", "$2 and 2 Gadgets are produced."]

Based on the information we have the most efficient producer of Gadgets is [choose one] ["DEF Corp.", "JKL Corp.", "GHI Inc.", "ABC Inc."]

If the price of Gadgets were $10 then we know that JKL Corp. [choose one] ["earns $2 of producer surplus per Gadget.", "earns -$2 or producer surplus per Gadget.", "earns $8 of producer surplus per Gadget.", "earns $10 of producer surplus per Gadget."]

If these producers have to bid against each other to produce one Gadget then [choose one] ["ABC Inc. produces it and needs to bid just under $4.", "ABC Inc. produces it and needs to bid just under $2.", "JKL Corp. produces it and needs to bid just over $6.", "JKL Corp. produces it and needs to bid just over $8."]