TASK DEFINITION: In this task, you are given a sentence. You must find the primary subject in the supplied sentence. The output must be a sub-sequence in the sentence.
PROBLEM: Rot-proofing was discontinued in 1963, because rot-proofed cordage has deteriorated in hot and humid conditions.

SOLUTION: Rot-proofing

PROBLEM: Construction and types.

SOLUTION: Construction

PROBLEM: Hemp is heavier than manila and the best quality is stronger than the manila supplied to the Royal Navy.

SOLUTION:
Hemp