The correct option is C Deploy
The word for the phrase 'To cause troops to spread out in readiness for battle' is option C, Deploy, i.e: it means to position the troops or establish them. Option A 'Align' means to place things in a straight line. Option B 'Collocate' means to set side by side, like collocates for the word 'mortgage' include 'lend' and 'property'. Option D 'Disperse' means to distribute or spread over a wide area. Thus, options A, B and D are incorrect and the correct option is option C, Deploy.