To "shore up" the main deck for the stowage of deck cargo means to

A
Weld pad eyes on deck in proper position to secure the cargo
B
Strengthen the main deck by placing pillars underneath it in the tween-decks
C
Distribute the weight of the cargo by placing fore-and-aft planks on the main deck
D
Package the cargo in wooden crates so it will not damage the deck
E