To find proof as to whether he is "in love" or not, Yukimura pats Himuro on the head from point-blank range. Seeing this, Ibarada, an upperclassman in the Ikeda Lab, talks about the need for a control experiment. In other words, in order to prove that the racing of his heart is because of Himuro specifically and not just because he's facing a woman, Yukimura has to pat Kanade and Ibarada on the head too. Himuro, on the other hand, sets out to prove that food made with love tastes better and cooks, but...
To investigate this, you need to run an 
experiment where "B" isn't there for comparison.
للتحقيق في الأمر، عليكما عمل تجربة لا يتواجد
 .فيها "ب" من أجل المقارنة
Zur Überprüfung muss ein Kontrollexperiment
stattfinden, bei dem B nicht vorkommt.
Per questa indagine, bisogna fare un esperimento
in una situazione in cui B non è presente.
Para investigar, precisa de um experimento
em que B não esteja na comparação.
Чтобы найти ответ, вам нужно провести 
эксперимент без участия в нём Б.