One / ones to replace countable nouns

a) Which keyboard would you like to have? – A silver and black (keyboard) {select: +one; ones}

b) I need a pen. Can I take that (pen) {select: +one; ones}?

c) They have sent us several proposals. The first two (proposals) {select: one; +ones} are quite essential.

d) If you need a specialist to upgrade your computer, I can recommend you a good (specialist) {select: +one; ones}.

e) Will you help me to carry my suitcases upstairs? – Which (suitcases) {select: one; +ones}?

f) Will you put this file onto the desk and the rest (files) {select: one; +ones} into the drawer?

g) You will see red and blue keys on the screen. Press the blue (key) {select: +one; ones}.

h) My computer can't identify this virus. – Perhaps, it's a new (virus) {select: +one; ones}.