You need Chemistry and another science/maths for most Pharmacy courses.
The other subject can literally be anything - so it makes sense to take a subject you will enjoy studying and where you are confident of a good grade. It could be in Dance, Accountancy or Underwater Basket Weaving - unless a Uni states clearly on the course page that 'x subject' is preferred, they really do not care what it is. So stop thinking 'what will impress them most' or 'what is most relevant' - if its not stated, then it really does not matter what that 3rd subject is.