Pepsi
vinegar
orange juice
a) they are all acidic.
b) they all taste bitter.
c) they all have a ph above 7.
d) they all turn litmus paper blue.

Let's eliminate the options one at a time.
A) They indeed all can donate an extra proton (or H+) so they are acidic. A is true.
B) They will not taste bitter, as acids, like those listed, will be sour. B is false
C) A pH above 7 means that something is basic, not acidic. C is false
D) Litmus paper turns blue when exposed to something basic, and red when exposed to something acidic. D is false.

The correct answer is A

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab. 

The answer is letter c