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.

This is made from tow, or from condemned cordage picked to pieces.
This

This process is called 'laying' and is always carried out in the opposite direction to that used in the previous stage of twisting the strands; it is, moreover, distinct from the simple spin or twist and is twofold, in that:
This process

Rope which is continually subjected to heat and damp - when in the tropics, for example - will lose its elasticity and strength sooner than rope used under normal conditions of temperature and humidity.
Rope