ACCA BPP Section B T Co - Practice and Revision Kit

Hi, Can you please help me understand the below question? the installation is expected to take one week to complete and would require three engineers, each of whom is paid a monthly salary of $4000.The engineers have just had their annually renewable contract renewed with T co. One of three engineers has spare capacity to complete the work but the other two would have to be moved from contract x in order to complete this one. Contract X generates a contribution of 200$ per engineer per week. There are no engineers available to continue with Contract X if these two engineers are taken off the job.it would mean that T co would miss its contractual completion deadline on Contract X by one week. As a result, T co would have to pay a one-off penalty of 500$.Since there is no other work scheduled for their engineers in one week’s time, it will not be a problem for them to complete contract x at this point. The question asks to: What figure should be included in the relevant cost statement for engineers' cost? The answer in the textbook is $500. My question is why isn't the VC and the opportunity cost of contribution foregone not included aswell?