Photo Size for Brochure

Hi all,
I am currently making a brochure using one of the templates on Graphicriver. The size of the brochure is A4. Can someone please tell me the best image size that I need to buy for this brochure? Most of the images will be about 10x5cm on paper but some will cover the full size of the page. Is the medium enough? The sizes are the following (example in pixles)

Medium 1756 x 1138 (2.0MP)
Large 3043 x 1972 (6.0MP)

I just want to make sure that I am buying the right size

Many thanks

300DPI A4 is 2480 x 3508

hi, indeed quality is never “too high”, so if u can opt for the biggest file … lol